Is the prayer invalidated if a man's private parts become unintentionally exposed briefly during prayer?
Chapter on the Description of Prayer
Al-Mughni
Book of Prayer
Primary text
If a worshipper's private parts become uncovered unintentionally and he covers them immediately without undue delay, the prayer remains valid. This is because a short duration of exposure is excused, resembling an excusable small measure of quantity. Al-Tamimi supported this view, citing the narration of Amr ibn Salama, holding that if the private parts were exposed briefly and then covered, there is no need to repeat the prayer.
Supporting text
The condition of the exposure being brief is necessary because prolonged exposure is egregious, avoidable, and thus not excused, similar to an excessive quantity of something else.