16:91
وَأَوْفُوا۟ بِعَهْدِ ٱللَّهِ إِذَا عَـٰهَدتُّمْ وَلَا تَنقُضُوا۟ ٱلْأَيْمَـٰنَ بَعْدَ تَوْكِيدِهَا وَقَدْ جَعَلْتُمُ ٱللَّهَ عَلَيْكُمْ كَفِيلًا ۚ إِنَّ ٱللَّهَ يَعْلَمُ مَا تَفْعَلُونَ
wa-awfū biʿahdi l-lahi idhā ʿāhadttum walā tanquḍū l-aymāna baʿda tawkīdihā waqad jaʿaltumu l-laha ʿalaykum kafīlan inna l-laha yaʿlamu mā tafʿalūna
Fulfil any pledge you make in God’s name and do not break oaths after you have sworn them, for you have made God your surety: God knows everything you do.
And fulfil the Covenant of Allâh (Bai‘ah: pledge for Islâm) when you have covenanted, and break not the oaths after you have confirmed them - and indeed you have appointed Allâh your surety. Verily! Allâh knows what you do.