Commentary on Tafsir al-Jalalayn: (( He knows )) that is, Allah (( the treachery of the eyes )) by their stealing glances at what is forbidden (( and what the breasts conceal )) the hearts

Then Allah, Blessed and Exalted is He, said: He knows: The doer is Allah, Mighty and Majestic. The treachery of the eyes: This is from the chapter of adding a description to the thing described, meaning the treacherous eyes. The treachery of the eye is its stealing a glance at a forbidden thing, meaning that a person may look at a forbidden thing while his companion is beside him and does not notice, because he is stealing the glance, as if he is waiting for an opportunity in his companion's unawareness to look at what Allah, Mighty and Majestic, has forbidden. This is one case.
Second: A person may look without stealing a glance, but openly, and his companion does not realize that he is looking with a forbidden gaze. Therefore, Allah, Mighty and Majestic, warned against this state and said: . The commentator said: "by their stealing glances at what is forbidden

and what the breasts conceal.

وما تخفي الصدور

[Ghafir 40:19]

the hearts". The author explained that the breasts are the hearts because they are in the breasts, as Allah the Exalted said: . Thus, Allah, Mighty and Majestic, clarified here the precision and subtlety of His knowledge, that He knows even this state which the people who are watching do not know. Yes.