Al-Isra 35

وَأَوْفُوا۟ ٱلْكَيْلَ إِذَا كِلْتُمْ وَزِنُوا۟ بِٱلْقِسْطَاسِ ٱلْمُسْتَقِيمِ ۚ ذَٰلِكَ خَيْرٌ وَأَحْسَنُ تَأْوِيلًا

wa-awfū l-kayla idhā kil'tum wazinū bil-qis'ṭāsi l-mus'taqīmi dhālika khayrun wa-aḥsanu tawīlan

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.