(30) “Tell the believing men to lower their gaze and guard their private parts. That is purer for them. Indeed, Allah is All-Aware of what they do.”
That is, direct the believers—those whose faith keeps them from falling into what undermines faith—and tell them to “lower their gaze” from looking at nakedness, women who are not their mahrams, beardless youths whose appearance may arouse temptation, and worldly adornments that tempt them and lead them into what is forbidden.
“And guard their private parts” from unlawful sexual acts, whether vaginal, anal, or of a lesser nature, and from allowing them to be touched or seen. “That”—guarding their gaze and private parts—“is purer for them”: it is cleaner and more wholesome, and causes their deeds to flourish. Whoever guards his private parts and his gaze is cleansed of the filth that defiles those who commit indecencies, and his deeds are purified because he refrains from the prohibited thing which (1) the soul craves and urges him toward. Whoever gives up something for Allah, Allah replaces it for him with something better; and whoever lowers his gaze from what is prohibited, Allah illuminates his inner sight.
Moreover, when a servant guards his private parts and his gaze from what is unlawful and from the means leading to it, despite the pull of desire, his ability to guard himself against anything else will be all the stronger. This is why Allah called it guarding. Anything entrusted to someone’s keeping will not remain secure unless its guardian diligently watches over it, protects it, and takes the measures necessary to preserve it. The same applies to one’s gaze and private parts: unless the servant strives to guard them, they will plunge him into afflictions and trials.
Notice how He commanded that the private parts be guarded without qualification, because neglecting to guard them is not permissible under any circumstances. Regarding the gaze, however, He said, “lower their gaze,” using the word min (“some of”), which indicates partiality. Looking is permissible in certain circumstances when there is a need, such as when a witness, a worker, or a suitor needs to look, and in similar cases. He then reminded them that He knows their deeds so that they would strive to protect themselves from prohibited things.