The Quran

وَإِلىٰ مَديَنَ أَخاهُم شُعَيبًا ۗ قالَ يا قَومِ اعبُدُوا اللَّهَ ما لَكُم مِن إِلٰهٍ غَيرُهُ ۖ قَد جاءَتكُم بَيِّنَةٌ مِن رَبِّكُم ۖ فَأَوفُوا الكَيلَ وَالميزانَ وَلا تَبخَسُوا النّاسَ أَشياءَهُم وَلا تُفسِدوا فِي الأَرضِ بَعدَ إِصلاحِها ۚ ذٰلِكُم خَيرٌ لَكُم إِن كُنتُم مُؤمِنينَ

Muhammad Asad

AND UNTO [the people of] Madyan [We sent] their brother Shu'ayb.¹ He said: "O my people! Worship God alone: you have no deity other than Him. Clear evidence of the truth has now come unto youfrom your Sustainer. Give, therefore, full measure and weight [in all your dealings], and do not deprive people of what is rightfully theirs;² and do not spread corruption on earth after it has been so well ordered: [all] this is for your own good, if you would but believe.

Shu'ayb is said to be identical with Jethro, the father-in-law of Moses, also called in the Bible Reu-el (Exodus ii, 18), meaning "Faithful to God". The region of Madyan - the Midian of the Bible - extended from the present-day Gulf of Aqabah westwards deep into the Sinai Peninsula and to the mountains of Moab east of the Dead Sea; its inhabitants were Arabs of the Amorite group of tribes.
Lit., "do not diminish to people their things" - an expression which applies to physical possessions as well as to moral and social rights. Regarding my interpolation of "in all your dealings", see surah 6, note 150.