Quran 70:30 — The Heights (Al-Ma'aarej)

إِلّا عَلىٰ أَزوٰجِهِم أَو ما مَلَكَت أَيمٰنُهُم فَإِنَّهُم غَيرُ مَلومينَ

(They have relations) only with their spouses, or what is legally theirs -

[70:29] They keep their chastity.

[70:31] anyone who transgresses these limits is a sinner.