قُلْ لِلْمُؤْمِنِيْنَ يَغُضُّوْا مِنْ أَبْصَارِهِمْ وَ يَحْفَظُوْا فُرُوْجَهُمْ, ذَلِكَ أَزْكَى لَهُمْ.

Say to the believing men that they should cast down their glances and guard their private parts (by being chaste). And this is better for them.