"And give full measure when you measure, and weigh with an even balance. That is the best [way]," meaning: when you provide full measure and maintain the weighing. "And best in result," meaning: in the outcome of the Hereafter. The meaning of "al-qistas" is: justice.
﴿وَأَوْفُوا الْكَيْلَ إِذَا كِلْتُمْ وَزِنُوا بالقسطاس الْمُسْتَقيم ذَلِك خير﴾ إِذَا أَوْفَيْتُمُ الْكَيْلَ، وَأَقَمْتُمُ الْوَزْنَ ﴿وَأحسن تَأْوِيلا﴾ يَعْنِي: عَاقِبَة الْآخِرَة. وَمعنى (القسطاس): الْعدْل.
