Tafsir of Ash-Shu`ara' 26:181

The Command to give Full Measure Allah commanded them to give full measure, and forbade them to give short measure. He said:

أوفوا الكيل وﻻ تكونوا من المخسرين

Give full measure, and cause no loss. meaning, `when you give to people, give them full measure, and do not cause loss to them by giving them short measure, while taking full measure when you are the ones who are taking. Give as you take, and take as you give.'

وزنوا بالقسطاس المستقيم