What is the 'awrah (private parts that must be covered) and what are its limits, and is the prayer likely to be invalid if the worshiper doubts that a part of his 'awrah has been uncovered?

Concealing one's awrah (private parts) means covering what is unsightly and causes embarrassment for both male and female. It is a condition for the validity of prayer, based on the Almighty's saying: "Take your adornment at every masjid (place of prayer)," and the Prophet's (peace be upon him) saying: "Allah does not accept the prayer of a menstruating woman unless she wears a khimar (head covering)."

A man's awrah in prayer is from the navel to the knee. A woman's awrah is her entire body, except for her face and palms.

If someone begins prayer with their awrah covered, then doubts during the prayer whether a part of it has become exposed, they should complete their prayer, because the default is that the covering remains, and a sudden doubt is not to be taken into account. The worshiper must wear clothing that completely covers their awrah and avoid short garments or those that might reveal the awrah during bowing and prostration.