1. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from al-Husayn ibn Sa‘id from Fadalah ibn Ayyub from al-Husayn ibn ‘Uthman from ibn Muskan from abu Basir who has said the following: “I once asked abu ’Abd Allah (a.s.), about a man who in a standing position doubts and does not know if he has performed Ruku‘ (bowing down on one’s knees) or not. He (the Imam) said, ‘He performs Ruku‘ and Sajdah (prostration).”’

Translation: Muhammad Sarwar·Thaqalayn link·The Arabic above is the original.

2. Ali ibn Ibrahim has narrated from his father from and Muhammad ibn ’Isma‘il from al-Fadl ibn Shadhan all from Ibn Abi ‘Umayr from Rifa‘ah who has said the following: “I once asked abu ‘Abd Allah (a.s.), about a man who forgets performing Ruku‘ (bowing down on one’s knees) until he performs Sajdah (prostration) and stands up. He (the Imam) said, ‘He performs Salah (prayer) again.’”

Translation: Muhammad Sarwar·Thaqalayn link·The Arabic above is the original.

3. Ali ibn Ibrahim has narrated from his father from Ibn Abi ‘Umayr from ‘Umar ibn ’Udhaynah from Zurarah who has said the following: “Abu Ja‘far (a.s.), has sad, ‘If one is certain that he has increased one Rak‘at in an obligatory Salah (prayer) he disregards it and performs that Salah (prayer) again if he has certainty.’”

Translation: Muhammad Sarwar·Thaqalayn link·The Arabic above is the original.