Al-Fath - 48:10

إِنَّ الَّذِينَ يُبَايِعُونَكَ إِنَّمَا يُبَايِعُونَ اللَّهَ يَدُ اللَّهِ فَوْقَ أَيْدِيهِمْ فَمَن نَّكَثَ فَإِنَّمَا يَنكُثُ عَلَى نَفْسِهِ وَمَنْ أَوْفَى بِمَا عَاهَدَ عَلَيْهُ اللَّهَ فَسَيُؤْتِيهِ أَجْرًا عَظِيمًا
[48:10]
Surely those who swear allegiance to you do but swear allegiance to Allah; the hand of Allah is above their hands. Therefore whoever breaks (his faith), he breaks it only to the injury of his own soul, and whoever fulfills what he has covenanted with Allah, He will grant him a mighty reward.
Verily those who plight their fealty to thee do no less than plight their fealty to Allah: the Hand of Allah is over their hands: then any one who violates his oath, does so to the harm of his own soul, and any one who fulfils what he has covenanted with Allah,- Allah will soon grant him a great Reward.
Lo! those who swear allegiance unto thee (Muhammad), swear allegiance only unto Allah. The Hand of Allah is above their hands. So whosoever breaketh his oath, breaketh it only to his soul's hurt; while whosoever keepeth his covenant with Allah, on him will He bestow immense reward.