Qur'an 70:30

إِلَّا عَلَىٰٓ أَزْوَٰجِهِمْ أَوْ مَا مَلَكَتْ أَيْمَـٰنُهُمْ فَإِنَّهُمْ غَيْرُ مَلُومِينَ

Save with their wives and those whom their right hands possess, for thus they are not blameworthy;