Tafseer Ibn Kathir of AL ISRAA' [35]

وَأَوْفُوا الْكَيْلَ إِذا كِلْتُمْ وَزِنُواْ بِالقِسْطَاسِ الْمُسْتَقِيمِ ذَلِكَ خَيْرٌ وَأَحْسَنُ تَأْوِيلاً

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