The Quran

وَلَو شاءَ اللَّهُ لَجَعَلَكُم أُمَّةً واحِدَةً وَلٰكِن يُضِلُّ مَن يَشاءُ وَيَهدي مَن يَشاءُ ۚ وَلَتُسأَلُنَّ عَمّا كُنتُم تَعمَلونَ

Muhammad Asad

For, had God so willed, He could surely have made you all one single community;¹ however, He lets go astray him that wills [to go astray], and guides aright him that wills [to be guided];² and you will surely be called to account for all that you ever did!³

I.e., bound by mutually agreed-upon moral values. See in this connection 10:19 and the corresponding notes, especially note 29. For an elucidation of the concept of ummah wahidah ("one single community") and its further implications, see surah 2, notes 197 and 198.
Or: "He lets go astray whomever He wills, and guides aright whomever He wills". Regarding the problem of free will versus predestination, seemingly implied in the concept of God's "letting man go [or "causing him to go"] astray" or, alternatively, "guiding him aright", see sdrah 14, note 4.
Alluding to the erroneous idea that man's good or evil actions - and therefore also his propensities and resulting attitudes - are "predetermined" by God and not really an outcome of free choice, Zamakhshari rounds off his views on this problem (quoted by me in surah 14, note 4) in these words: "If [it were true that] God compels [men] to astray or, alternatively, to follow His guidance - why should He have postulated their deeds as something for which they will be held responsible?"