What is the validity of the prayer if one performs Sujud in the position of Ruku' believing it to be obligatory or permissible?
General Chapter
Al-Mughni
Book of Friday Prayer
Primary text
If one performs Sujud while believing it to be forbidden (i.e., performing Sujud instead of Ruku' when the Imam is bowing), the prayer is invalid because a mandatory act was intentionally omitted, and an impermissible act was performed. If one performs Sujud believing it to be permissible while the Imam is bowing, this Sujud is not counted because it was performed in the place of Ruku' out of ignorance, making the individual similar to one who forgot. If they then catch the Imam in Ruku', that Ruku' counts, and the second Rak'ah is validated as the first.
Supporting text
If the person starts the second Rak'ah or any intended act of it after completing the two Sujuds without standing up (i.e., remaining seated for the Sujuds), the first Rak'ah is validated, according to a position derived from the invalidation of the first Rak'ah if one rises for the second prematurely. Abu al-Khattab stated that if one performs Sujud believing it permissible, it counts, and the Rak'ah is valid, similar to performing Sujud while the Imam is standing.