Allaah (The Most High) said:

أَوۡفُواْ ٱلۡكَيۡلَ وَلَا تَكُونُواْ مِنَ ٱلۡمُخۡسِرِينَ

وَزِنُواْ بِٱلۡقِسۡطَاسِ ٱلۡمُسۡتَقِيمِ

وَلَا تَبۡخَسُواْ ٱلنَّاسَ أَشۡيَآءَهُمۡ وَلَا تَعۡثَوۡاْ فِى ٱلۡأَرۡضِ مُفۡسِدِينَ

وَٱتَّقُواْ ٱلَّذِى خَلَقَكُمۡ وَٱلۡجِبِلَّةَ ٱلۡأَوَّلِينَ

“Give full measure, and cause no loss (to others).”And weigh with the true and straight balance. “And defraud not people by reducing their things, nor do evil, making corruption and mischief in the land. “And fear Him Who created you and the generations of the men of old.” [26:181-184]