The Quran

۞ وَإِلىٰ مَديَنَ أَخاهُم شُعَيبًا ۚ قالَ يا قَومِ اعبُدُوا اللَّهَ ما لَكُم مِن إِلٰهٍ غَيرُهُ ۖ وَلا تَنقُصُوا المِكيالَ وَالميزانَ ۚ إِنّي أَراكُم بِخَيرٍ وَإِنّي أَخافُ عَلَيكُم عَذابَ يَومٍ مُحيطٍ

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; and do not give short measure and weight [in any of your dealings with men].² Behold, I see you [now] in a happy state; but, verily, I dread lest suffering befall you on a Day that will encompass [you with doom]!

See surah 7, note 67.
Thus, belief in the One God and justice in all dealings between man and man (see surah 6, note 150) are here placed together as the twin postulates of all righteousness. Some commentators assume that the people of Madyan were of a particularly commercial bent of mind, and given to fraudulent dealings. It is obvious, however, that the purport of this passage and of its sequence goes far beyond anything that might be construed by a purely "historical" interpretation. What this version of Shu'ayb's story aims at is - as always in the Qur'an - the enunciation of a generally applicable principle of ethics: namely, the impossibility of one's being righteous with regard to God unless one is righteous - in both the moral and social senses of this word - in the realm of human relationships as well. This explains the insistence with which the above prohibition is re-stated in a positive form, as an injunction, in the next verse.