Ayah

قُل لِّلۡمُؤۡمِنِينَ يَغُضُّواْ مِنۡ أَبۡصَٰرِهِمۡ وَيَحۡفَظُواْ فُرُوجَهُمۡ ۚ ذَٰلِكَ أَزۡكَىٰ لَهُمۡ ۗ إِنَّ ٱللَّهَ خَبِيرٌ بِمَا يَصۡنَعُونَ
Translation

Say to the believing men that they should lower their gaze and guard their modesty: that will make for greater purity for them: And Allah is well acquainted with all that they do.<br/>
Tafsir

Tell believing men to lower their gaze, from what is unlawful for them to look at (min [of min absaarihim, 'their gaze'] is extra) and to guard their private parts, from doing with them what is unlawful [for them to do]. That is purer, in other words, better, for them. Truly God is Aware of what they do, with their gazes and private parts, and He will requite them for it.