As an Islamic principle, jihad has always been praised and Allah (SWT) has put forth this issue in many verses of the Quran. But the attitude toward jihad does not imply that Muslims should never accept truce or reconcile in order to reach peace nor does it mean that jihad should always be on the agenda. As per the Holy Quran, Allah (SWT) rejects this attitude seeking an interplay between war and peace Allah says: "And if they incline to peace, then incline to it and trust in Allah" [1] Believers, however, should be wary so that their enemy does not intend to deceive them and use the truce as an opportunity to launch a surprise attack or to postpone war to gather more troops[2]:

«وَ إِن یُرِیدُواْ أَن یخدَعُوکَ فَإِنَّ حَسْبَکَ اللَّهُ هُوَ الَّذِى أَیَّدَکَ بِنَصْرِهِ وَ بِالْمُؤْمِنِینَ»

"And if they intend to deceive you-- then surely Allah is sufficient for you; He it is Who strengthened you with His help and with the believers"[3]
Meanwhile Allah (SWT) reassures His prophet that even if the enemy have such an intention, He will help His Prophet. Then He gives an example of His assistance:

«وَ أَلَّفَ بَینْ‏َ قُلُوبهِمْ  لَوْ أَنفَقْتَ مَا فىِ الْأَرْضِ جَمِیعًا مَّا أَلَّفْتَ بَینْ‏َ قُلُوبِهِمْ وَ لکِنَّ اللَّهَ أَلَّفَ بَیْنَهُم إِنَّهُ عَزِیزٌ حَکِیمٌ».

"And united their hearts; had you spent all that is in the earth, you could not have united their hearts, but Allah united them; surely He is Mighty, Wise"[4]
Surely it has been Allah (SWT) who created unity and a sense of empathy among the Holy Prophet's allies. The army under his command was composed of the same people who were enemies of each other fighting several wars to decimate and destroy each other. They would have never become comrades and come together and united on any basis, if Allah (SWT) did not will.
To have a better understanding of the verse some points should be taken into account:
1-More attention should be paid to the instance or manifestation of this conditional clause: "And if they intend to deceive you" Since this verse and the previous verses are about jihad, it can be concluded that polytheists are certainly the points of reference of these verses[5]. However the verse can include hypocrites as well. Then it would mean that if some people in the guise of Islam deceive you and accost you, accept them. Some traditions imply that this verse is about hypocrites: "They were a group of Quraysh who had accompanied the holy Prophet, peace be upon him and his descendants[6]  this is a clause about hypocrites who were among the Prophet's followers but they were mentally tilted to the opposite side. If we consider this verse applicable to hypocrites as well we should say that truce in the previous verse has a different meaning; because peace and ceasefire with a group who are with the prophet at least apparently is meaningless; therefore this verse can mean condoning and tolerating hypocrites as long as they have not performed specific action against the Prophet because in another verse[7] war with the hypocrites has been interpreted as a form of vigorous action against them.
2- From the outward meaning of the verse "And if they intend to deceive you-- then surely Allah is sufficient for you", it may occur to us that if enemies extended their hands for friendship although it is clear that they have intended to deceive us, then as Muslims we should have peace with them and meanwhile seek refuge to Allah (SWT) from their conspiracies and tricks. This reasoning suffers from two problems:
a) Obviously the intellect rules that a truce which in favor of the enemy and against the person should not be accepted and a person who is about to prepare himself to attack us should not be given more time:
b) This interpretation is in contrast with the explicit meaning of other verses of Quran which says:

«وَ إِمَّا تخَافَنَّ مِن قَوْمٍ خِیَانَةً فَانبِذْ إِلَیْهِمْ عَلىَ‏ سَوَاءٍ  إِنَّ اللَّهَ لَا یحُبُّ الخْائنِین».

"And if you fear treachery on the part of a people, then throw back to them on terms of equality; surely Allah does not love the treacherous"[8]
Therefore the verse in question should be interpreted as below: If there is no sign of treachery in their peace and even it seems that they will keep their promises it is better to accept peace and Muslims should seek refuge to Allah (SWT) from any possible conspiracy of which Muslims are unaware and Allah (SWT) is sufficient for them[9].
3- The clause "And united their hearts" refers to two tribes called "Aus" and "Khazraj" [10] who were enemies prior to the advent of Islam. The Prophet, peace be upon him and his family, created peace and friendship among them. This is inferred from some traditions: "And united their hearts refers to ansar i.e. aus and khazraj who were in war constantly and Allah (SWT) united their hearts and helped His prophet… "[11]  However some exegetes of the Holy Quran have generalized the meaning to include mohajerin [those who migrated from Mecca to Medina] and ansar [residents of Medina] etc[12]

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