﴿ وَيَٰقَوْمِ أَوْفُوا۟ ٱلْمِكْيَالَ وَٱلْمِيزَانَ بِٱلْقِسْطِ ۖ وَلَا تَبْخَسُوا۟ ٱلنَّاسَ أَشْيَآءَهُمْ وَلَا تَعْثَوْا۟ فِى ٱلْأَرْضِ مُفْسِدِينَ ﴾

“Hence, O my people, [always] give full measure and weight, with equity, and do not deprive people of what is rightfully theirs, and do not act wickedly on earth by spreading corruption.”

Obviously, the very prohibition of weighing and measuring short makes weighing and measuring in full necessary. But, to emphasize it further, Sayyidna Shu'aib علیہ السلام said: وَيَا قَوْمِ أَوْفُوا الْمِكْيَالَ وَالْمِيزَانَ بِالْقِسْطِ ۖ وَلَا تَبْخَسُوا النَّاسَ أَشْيَاءَهُمْ وَلَا تَعْثَوْا فِي الْأَرْ‌ضِ مُفْسِدِينَ And 0 my people, perfect the measure and the balance with justice and do not make the people short of their things, and do not go about the earth spreading disorder - 85.