Why do Muslims pray with bowing and prostration?

Because in prayer the whole person stands before God, not just the mind. The postures express with the body what the heart feels, and prostration brings a person closest to God.

Many people think of prayer as something done quietly while sitting or with folded hands. The Islamic prayer is different. It consists of standing, bowing, prostrating and sitting. Muslims did not invent this form themselves. The Holy Qur’an explicitly mentions bowing and prostration, as the first verse above shows.

A human being is not only a mind. Body and soul affect each other. Someone who is sad lets their shoulders drop, and someone who is happy stands up straight. In the same way, the posture of the body shapes what is inside. Prayer makes use of this connection. The body expresses what the heart means.

Each posture has its meaning. Standing, a person stands respectfully before their Lord. Bowing, they bend before His greatness. In prostration they place their forehead on the ground, the part of the body one normally carries highest. There is hardly a deeper gesture of humility. That is exactly why, according to the first hadith above, a person is closest to God in that moment.

This does not mean that God accepts prayer only in this form. Someone who is ill or elderly and cannot stand or prostrate prays sitting or even lying down. The second hadith above expressly allows this. The movements are a gift for those who can perform them, not an obstacle for those who cannot.

The deeper meaning of each posture of prayer is a wide subject. To begin with, it is enough to know that prayer involves the whole person, so that they can turn to God with all that they are.