What should a worshiper do if they reach the bowing position and forget the takbir – should they say it while bowing or perform the prostration of forgetfulness (sujud as-sahw)?

Whoever misses the transition takbir for bowing is not permitted to perform it while bowing because its place has passed. Whoever omits it due to forgetfulness should perform the prostration of forgetfulness ( sujud al-sahw) before the taslim.