would—whenever the revelations of the Most Compassionate were recited to them—fall down in prostration, weeping (19:58);
and that “those who were given knowledge beforehand, when it is recited to them, fall upon their chins in prostration,” and
“they fall upon their chins weeping” (17:107-109).

This is because falling down (khurūr) is the first gesture of submission that stands in direct opposition to pride. The arrogant detest having to lower themselves; they prefer to remain constantly upright and elevated, for falling down entails abasement, humility, and reverence. For this reason, the haughty—Arab and non-Arab alike—shrink from doing it. If something slipped from one of them, he would refuse to pick it up lest he have to bend over and lower himself.

Falling down means lowering the face and the head, the highest and noblest part of a human being. Man was created upright; when he lowers this part of himself—especially in prostration—that is the utmost degree of self-abasement. Therefore prostration is suitable only for Allah. Whoever prostrates to other than Him is a polytheist, and whoever refuses to prostrate to Him is arrogantly turning away from His worship; both are unbelievers destined for the Fire.

Allah, exalted is He, says:
“Your Lord has said, ‘Call upon Me and I will answer you. Indeed, those who wax proud against My worship shall enter Hell in humiliation’” (40:60).

He also says:
“And among His signs are the night and the day, the sun and the moon. Do not prostrate yourselves to the sun nor to the moon; rather, prostrate yourselves to Allah who created them, if it is Him you truly worship” (41:37).

And in the story of Bilqīs He says:
“I found her and her people prostrating to the sun instead of Allah…” (27:24).