What is the ruling on one who doubts or remembers forgetting a ruk'ah or a fard during or after the prayer, and how is that rectified with the two prostrations of forgetfulness (sujood as-sahw)?

The rulings concerning forgetfulness (in prayer) are numerous and require consulting scholars. Whoever omits a pillar or a complete rak'ah (unit of prayer) must perform what they omitted, and prostration of forgetfulness (sujood al-sahw) alone is not sufficient for these omissions. If one doubts having omitted a pillar or a rak'ah before the tasleem (salutation to end the prayer), they must perform what they are doubtful about, and then perform the prostration of forgetfulness, based on the hadeeth of Abu Sa'id: "If one of you doubts in his prayer and does not know how many (rak'ahs) he has prayed, three or four, let him cast away doubt and base (his prayer) on what he is certain of, then let him prostrate twice before giving the tasleem."