Surah An-Nahl 16:91

وَأَوْفُوا۟ بِعَهْدِ ٱللَّهِ إِذَا عَـٰهَدتُّمْ وَلَا تَنقُضُوا۟ ٱلْأَيْمَـٰنَ بَعْدَ تَوْكِيدِهَا وَقَدْ جَعَلْتُمُ ٱللَّهَ عَلَيْكُمْ كَفِيلًا ۚ إِنَّ ٱللَّهَ يَعْلَمُ مَا تَفْعَلُونَ

And fulfill the covenant of Allāh when you have taken it, [O believers], and do not break oaths after their confirmation while you have made Allāh, over you, a security [i.e., witness]. Indeed, Allāh knows what you do.

Translation: Saheeh International

Tafsir

And fulfil God’s covenant effected by way of pledges of allegiance and oaths and in other ways when you made a covenant and do not break your oaths after pledging them and having made God surety over you that you will fulfill the covenant for you have sworn the oath by Him the sentence wa-qad ja‘altumu’Llāha ‘alaykum …

Excerpt from Tafsir al-Jalalayn, commentary on 16:91, via Quran.com. The reader has the full commentary and 9 more tafsirs.