• قِسْطَاس

Appears 2 times in the Quran.

1. 17:35 وَأَوْفُوا۟ ٱلْكَيْلَ إِذَا كِلْتُمْ وَزِنُوا۟ بِٱلْقِسْطَاسِ ٱلْمُسْتَقِيمِ ذَٰلِكَ خَيْرٌ وَأَحْسَنُ تَأْوِيلًا

   And give full measure when you measure out, and weigh with a true balance; this is fair and better in the end.
   

2. 26:182 وَزِنُوا۟ بِٱلْقِسْطَاسِ ٱلْمُسْتَقِيمِ

   And weigh (things) with a right balance,