What is the ruling for someone who forgot to perform rukūʿ (bowing) and did not remember until they were prostrating (sājid)? Are they required to stand up and then bow, or is it sufficient for them to bow directly?

Whoever forgets the bowing (rukūʿ) and remembers it during prostration (sujūd) should stand up from prostration, straighten himself to a standing position, and then bow. He should not merely go down from prostration directly into bowing. The ma'mūm (follower) catches up with the bowing before the imām (leader) bows in the next rakʿah (unit of prayer). The rakʿah whose pillar was forgotten is nullified if one begins reciting in the subsequent rakʿah, according to the Hanbalis, or if one performs the bowing of the subsequent rakʿah, according to the Malikis, and the subsequent rakʿah takes its place.