إِنَّ ٱلَّذِينَ يُبَايِعُونَكَ إِنَّمَا يُبَايِعُونَ ٱللَّهَ يَدُ ٱللَّهِ فَوْقَ أَيْدِيهِمْ ۚ فَمَن نَّكَثَ فَإِنَّمَا يَنكُثُ عَلَىٰ نَفْسِهِۦ ۖ وَمَنْ أَوْفَىٰ بِمَا عَـٰهَدَ عَلَيْهُ ٱللَّهَ فَسَيُؤْتِيهِ أَجْرًا عَظِيمًا
inna alladhīna yubāyiʿūnaka innamā yubāyiʿūna l-laha yadu l-lahi fawqa aydīhim faman nakatha fa-innamā yankuthu ʿalā nafsihi waman awfā bimā ʿāhada ʿalayhu l-laha fasayu'tīhi ajran ʿaẓīman
Those who pledge loyalty to you [Prophet] are actually pledging loyalty to God Himself- God’s hand is placed on theirs––and anyone who breaks his pledge does so to his own detriment: God will give a great reward to the one who fulfils his pledge to Him.
Verily, those who give Bai‘ah (pledge) to you (O Muhammad صلى الله عليه وسلم) they are giving Bai‘ah (pledge) to Allâh. The Hand of Allâh is over their hands. Then whosoever breaks his pledge, breaks it only to his own harm; and whosoever fulfils what he has covenanted with Allâh, He will bestow on him a great reward.