Quran 70:30

إِلَّا عَلَىٰٓ أَزۡوَٲجِهِمۡ أَوۡ مَا مَلَكَتۡ أَيۡمَـٰنُہُمۡ فَإِنَّہُمۡ غَيۡرُ مَلُومِينَ ٣٠

(They have relations) only with their spouses, or what is legally theirs. They are not to be blamed.