Is the prayer of one who wears a thick, opaque garment without long trousers beneath it valid, if some of his thigh becomes slightly exposed during prostration when his feet are not kept together?

Prayer is valid in a covering garment without trousers; a waist-wrapper (izar) is sufficient to cover the lower part of the body. This was indeed among the clothing of the Prophet, peace and blessings be upon him, and of pilgrims performing Hajj and Umrah. However, it is necessary to be mindful of covering what is between the navel and the knee for a man during prayer, which is the opinion of the majority of jurists. Others have held that the thigh is not awrah (private parts), but the opinion of the majority is more cautious. Covering the awrah is a condition for the validity of prayer. Thus, if the lower part of the thigh becomes exposed during prostration due to the garment being too short or tight, the prayer is not valid. However, if the garment is long and covering, and the lower part of the thigh becomes exposed because the worshiper is in a higher position, the prayer is valid, because the obligatory covering is from above and the sides, not from below.