Humility towards the believers and being stern towards the disbelievers is obligatory due to the saying of Allah (swt): 

''O you who believe! Whoever from among you turns back from his religion (Islam), Allah will bring a people whom He will love and they will love Him; humble towards the believers, stern towards the disbelievers, fighting in the Way of Allah, and never afraid of the blame of the blamers. That is the Grace of Allah, which He bestows on whom He wills. And Allah is All Sufficient for His creatures' needs, All Knower.''[ Al-Maa'idah:54]the word humility (zillah) here means mercy, compassion and leniency and should not be confused with the word zull which means disgrace and humiliation. The word 'izzah means sternness, harshness, enmity and defeat. It is said that the expression 'azzahu means he defeated him. The land which is 'izaazis the firm and rigid land due to his (swt) saying: 

''Muhammad (SAW) is the Messenger of Allah, and those who are with him are severe agains disbelievers.''[ Al-Fath:29] Also, Allah (swt) ordered his Messenger (saw) to make himself gentle (lower his wings) to the believers. He (swt) says: 
''And be kind and humble to the believers who follow you.'' [ash-Shu'araa':215] 

i.e. be lenient towards them and show kindness. He (swt) forbade him to be harsh with them when He said: 

''And by the Mercy of Allah, you dealt with them gently. And had you been severe and harsh-hearted, they would have broken away from about you; so pass over (their faults), and ask (Allah's) Forgiveness for them; and consult them in the affairs. Then when you have taken a decision, put your trust in Allah, certainly, Allah loves those who put their 
trust (in Him).'' [ Aali 'Imraan:159] 

while He (swt) orders His Messenger to be compassionate and lenient and forbids him from being stern towards the believers at the same time He orders the Messenger to be harsh towards the Kuffar and the hypocrites: 

''O Prophet (Muhammad SAW)! Strive hard against the disbelievers and the hypocrites, and be harsh against them, their abode is Hell, - and worst indeed is that destination.''[ at-Tawbah:73] 

The address (khitaab) to the Messenger (saw) is an address to his Ummah as long is there is no evidence of specification. The believer is obliged to be compassionate, show mercy and leniency and and make himself gentle to the believers and be stern, harsh, hostile and defeating to the Kuffar. He (swt) says: 
''O you who believe! Fight those of the disbelievers who are close to you, and let them find harshness in you, and know that Allah is with those who are the Al-Muttaqun (the pious).'' [ at-Tawbah:123]

The Sunnah has confirming this issue. Thus, in the hadith of an-Nu'man b. Basheer (ra) it is narrated that the Messenger of Allah (saw) says: 

''The example of the believers in their mutual love, compassion and empathy is like that of a body. If one part is hurt then the rest of the body calls out in sleeplessness and fever.'' 

Muslim  reported on the authority of 'Iyaad b. Himaar (ra) who said: I heard the Messenger of Allah (saw) say: 
''The people of Jannah are three; a ruler who is just, gives alms and brings reconciliation, a man who is soft hearted and compassionate to his relatives and all Muslims, and a man who is chaste and virtuous having lot of children but with little means.''

In the hadith of Jabir b. 'Abd it is narrated that the Messenger of Allah (saw) said: 

''The one who shows no compassion will not be shown any compassion.''

Being deprived of compassion i.e. the compassion of Allah is an indication that compassion towards the believers is obligatory. Also indicating the obligation of mutual compassion is the hadith narrated by Ibn Hibbaan in his Sahihon the authority of Abu Hurayrah who said: I heard Abul Qasim, the honest and trustworthy, say: 
 
''Mercy is not taken away except from one who is wretched and nasty.'' 

Also what Muslim narrated on the authority of 'Ayisha who said; I heard the Messenger of Allah (saw) say in my house: 

''O Allah whoever has been given authority over the affaires of my Ummah and was harsh with them, then be harsh with him. And whoever has been given authority over the affaires of my Ummah and was kind with them, then show him kindness.'' 

If someone claims that the request for mercy has come in the general form and it includes all people whether they be Muslim, Kaafir, hypocrite, obedient or disobedient due to the hadith of Jabir b. 'Abdullah reported by Muslim where the Messenger of Allah (saw) said: 

''Allah will not show compassion to the one that does not show compassion to the people.'' 

It is correct that the expression 'people' is general ('aam) but it is a general expression from which the specific is intended such as in His (swt) saying: 

''Those (i.e. believers) unto whom the people (hypocrites) said, ''Verily, the people (pagans) have gathered against you (a great army).''[ 3:173] 

Narrations about the Messenger's mercy for the believers can be seen in what the two Shaykhs reported on the authority of 'Abd Allah b. 'Umar who said: 

Sa'd b. 'Ubaadah became sick and the Prophet along with 'Abd ar-Rahman b. 'Awf, sa'd b. Abi Waqqas and 'Abdullah b. Mas'ud visited him to inquire about his health. When he came to him, he found him surrounded by his household and he asked: ''Has he died?'' They said, ''No, O Allah's Messenger.'' The Prophet wept and when the people saw the weeping of Allah's Messenger they all wept. He said: ''Will you not listen? Allah does not punish for shedding tears, nor for the grief of the heart but he punishes or bestows His Mercy because of this.'' 

Also the hadith reported by at-Tirmizi, which he said is hasan sahih, on the authority of 'Ayisha ''The Prophet (saw) kissed 'Uthman b. Maz'un when he died. He wept (or the narrator said his eyes were flowing with tears).

Muslim reported on the authority of Anas (ra): ''The Prophet (saw) did not enter the presence of any women except his wives and except Umm Saleem. He used to enter her presence, and when asked about it he said: 'I have compassion for her, her brother was killed with me (whilst in battle).'' 

An example of his leniency towards the believers is what al-Bukhari reported from 'Abd Allah b. 'Umar who said: 

''The Prophet (saw) besieged the Taa'if but was not able to open it. The Prophet (saw) said: ''We are returning home tomorrow, if Allah wills. The Muslims said: 'do we return? But we have not opened Taa'if?'' He said: Be ready in the morning to fight.' They were ready to fight the next morning but they sustained many injuries. The Prophet (saw) said: ''We are  returning home tomorrow, if Allah wills.'' This seemed to please the Sahabah, Allah's Messenger smiled. 

An example of his kindness for the believers is what Muslim reported on the authority of Mu'awiyyah b. al-Hakam as-Salami who said: 

''I was praying behind the Messenger of Allah and someone in the congregation sneezed. I said [to him]: 'May Allah have mercy upon you.' The people then stared at me, showing their disapproval of my act. I said: 'Woe to me, why do you stare at me so?' They started to strike their hands on their thighs and when I saw that they wanted me to become silent, I was angered but said nothing. When the Messenger of Allah finished the prayer - and may my father and mother be ransomed for him, I found no teacher better than him either before or after him - he did not scold, beat, or revile me but he simply said: 'Talking to others is not seemly during the salah(prayer), for the salah is for glorifying Allah, extolling His Greatness, and reciting the Qur'an.''

Also the hadith reported by al-Bukhari on the authority of Anas (ra) who said: 

While I was walking with the Prophet who was wearing a Najrani outer garment with a thick hem, a bedouin came upon the Prophet and pulled his garment so violently that I could see the impression of the hem of the garment on his shoulder, caused by the violence of his pull. Then the bedouin said, ''Order for me something from Allah's fortune which you 
have.'' The Prophet turned to him and smiled, and ordered that a gift be given to him. 

Muslim reported on the authority of Anas (ra) who said that after the death of Allah's Messenger Abu Bakr said to 'Umar: come, let us visit Umm Ayman as the Messenger of Allah (saw) used to visit her. When we reached her place she began to weep. They said: what makes you cry? What Allah has is better for His Messenger. She said: I am not crying because I do not know that what Allah has is better for His Messenger. I am crying because the revelation from the heavens has come to an end. Her words moved them so much that both of them began to weep with her. 

Muslim reported a long hadith on the authority of 'Umar b. al-Khattab regarding the ransoming of the prisoners of Badr: the next day I came while the Messenger of Allah (saw) and Abu Bakr were sitting and crying. I said: O Messenger of Allah, tell me what is making you and your friend to weep. If I find a reason to cry then I will cry and if I don't find a reason then I will pretend to cry with you..'

Ibn 'Abd al-Barr reported in al-Istee'aabon the authority of Janaadah b. Abi Umayyah that 'Ubaadah b. Saamit was in charge of fighting at Alexandria, and he had prevented them from fighting but they fought. So he called upon me and said: O Junadah, reach the people. So I went there and returned back to him. He asked: Has any body been killed? I said: No. He said: Praise is to Allah that not one of them was killed while being disobedient. 

Here we need to clarify the distinction between showing mercy, leniency and compassion amongst Muslims and being firm and strong with them. What must be apparent is that there is no mercy, compassion or leniency in the application of the Sharee'ah rule and matters of harm to the Muslims. Here one must be strong and firm in applying the rules and preventing any harm to the Muslims. The following is a clarification of that which relates to the application of the Sharee'ah rule: 

The above hadith of Abu Hurayrah as reported by Ahmad in which the Messenger of Allah (saw) said: 

''Beat him,' 'and then afterwards he would say: ''say may Allah have mercy on you.'' 

 In Hudaybiyyah he (saw) went against their opinion because the issues relates to a Sharee'ah rule. The hadith in this regard is known. He did know show any compassion in order to avoid putting them in difficulty i.e. under the pretext of having mercy, compassion and leniency like those who go agent his command.

 In the hadith of 'Ayisha (ra) it is narrated that she said: Quraysh were concerned about a woman from Banu Makhzoom who had stole something. They said who will speak Allah's Messenger about her. They said: ''who can dare to do this except Usaamah the one that Allah's Messenger loves.'' So Usaamah spoke to him. The Messenger of Allah (saw) said to him: ''are you interceding for a Hadd of Allah?'' Then he stood and addressed the people: ''O people, those before you were destroyed because when the noble amongst them stole they left him but when the poor amongst them stole they applied the Hadd upon him. By Allah! Had Faatimah the daughter of Muhammad stole then I would have cut her hand off.''He was not lenient to the Quraysh, he did not show compassion to the woman from Banu Makhzum and he rejected the intercession of Usaamah.'' (Agreed upon) 

Had the Messenger of Allah (saw) been merciful to anyone regarding the application of the Sharee'ah rule he would have done so with al-Hasan b. 'Ali when he took a date allotted for charity. Abu Hurayrah (ra) narrated that 'al-Hasan b. Ali took date from the sadaqah and put it in his mouth. The Messenger of Allah (saw) said: 

'Yuk, yuk, spit it out. Do you not know we do not eat Sadaqah?!’' (Agreed upon) 

As for the Prophet's (saw) resolve in repelling a harm this is clear from the Hadith of Mu'az reported by Muslim in the expedition of Tabuk: The Messenger of Allah (saw) said: 

''Tomorrow you will come, insha' llah, to the spring of Tabuk. But you will not get there until well into the morning. No one who arrives should touch any of its water until I come.' 

We came to it and two men had got to it before us and the spring was dripping with a little water. The Messenger of Allah (saw) asked them, 'Have you touched any of its water?' They said, 'Yes.' The Messenger of Allah, May Allah bless him and grant him peace, reviled them and said what Allah wished him to say.'' 

As for the resolve of the Sahabah the most prominent example is what Abu Bakr did in respect to fighting the apostates, sending the army of Usaamah against the wishes of all the Muslims. They acceded to his opinion, executed his command and then praised him. If we excluded the application of the Sharee'ah which includes repelling the harm then one cay say: those people who are shown compassion are those who have been hit by a misfortune such as death, illness, loss of a loved one; as for the ignorant person he should be shown compassion and leniency whilst teaching him and being patient. In applying the permissible (mubah) one should choose the easiest option, prefer leniency to strictness as the Messenger (saw) did when he besieged Taa'if, as mentioned above 
in the hadith of Ibn 'Umar reported by al-Bukhari.

What remains now is to give a picture of the harshness of the Muslims for the Kuffar: 
In battle: 
A Hadith of Wahshi reported by al-Bukhari in which he said: ''When the people set out (for the battle of Uhud) in the year of 'Ainain ('Ainain is a mountain near the mountain of Uhud, and between it and Uhud there is a valley) I went out with the people for the battle. When the army aligned for the fight, Siba' came out and said, 'Is there any (Muslim) to accept my challenge to a duel?' Hamza bin 'Abdul Muttalib came out and said, 'O Siba! O Ibn Um Anmar, the one who circumcises other ladies! Do you challenge Allah and His Messenger?' Then Hamza attacked and killed him, causing him to be non-extant like the bygone yesterday..'' 

Second: in negotiations: 

The hadith of al-Miswar and Marwaan reported by al-Bukhari which states: Urwa kept on talking to the Prophet and seizing the Prophet's beard as he was talking while Al-Mughira bin Shu'ba was standing near the head of the Prophet, holding a sword and wearing a helmet. Whenever Urwa stretched his hand towards the beard of the Prophet, Al-Mughira would hit his hand with the handle of the sword and say (to Urwa), ''Remove your hand from the beard of Allah's Messenger.'' 

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