Quran 13:20 from Surah Ar-Ra'd on Divine Marvels.
ٱلَّذِينَ يُوفُونَ بِعَهۡدِ ٱللَّهِ وَلَا يَنقُضُونَ ٱلۡمِيثَٰقَ
English translation: Those who fulfill the covenant (of) Allah and not they break the contract
Transliteration: alladhina yufuna bi'ahdi al-lahi wala yanquduna al-mithaqa