The one who casts evil glances is breaching the trust of Allah Ta'ala. Allah Ta'ala says:

? ???? ????? ?????? ??? ???? ?????? ?

"He knows the mistrust of the eyes and that which the hearts conceal." (Sura Mumin; Ayat 18, Juz 24)

Allah Ta'ala uses the word ?????, which means to commit mistrust. This indicates that we are not the owners of our eyes rather we have been entrusted with them. This is the reason why suicide is forbidden, because we are not owners of our bodies. Allah Ta'ala has entrusted us with our bodies. Since they are a trust from Allah Ta'ala, to use it against His pleasure, to harm it or to put an end to it is forbidden. If we were owners of our bodies then perhaps we would have the right to use them the way we desire. By not giving us the choice and freedom to utilize our bodies, the way we desire is the proof that this is a trust from Allah Ta'ala. To embezzle this trust of Allah Ta'ala is a great crime. The one who casts evil glances is breaching and embezzling the trust of sight which Allah Ta'ala has granted him. The breacher of this trust cannot become the friend of Allah Ta'ala. How beautifully a poet has said:

??? ?? ??? ?? ?? ?? ???? ?? ??? ?????

?? ????  ????  ????   ???  ???  ????   ????

The "thief of sight" can never have the crown of friendship placed upon his head

He who is not a Muttaqi, is not a Wali