Surah Al-Isra, ayah 35

وَأَوۡفُواْ ٱلۡكَيۡلَ إِذَا كِلۡتُمۡ وَزِنُواْ بِٱلۡقِسۡطَاسِ ٱلۡمُسۡتَقِيمِۚ ذَٰلِكَ خَيۡرٞ وَأَحۡسَنُ تَأۡوِيلٗا ٣٥

Wa awful-kayla idhā kiltum wazinū bil-qistāsil-mustaqīmi dhālika khayrun wa ahsanu ta'wīlā

And give full measure when you measure, and weigh with an even [i.e., honest] balance. That is the best [way] and best in result.