Iyad narrates that he asked Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him): "One of us prays and does not remember how many rak'ahs he has prayed." He said that the Messenger of Allah (peace and blessings be upon him) said to us: "When one of you prays and does not remember how many rak'ahs he has prayed, let him perform two prostrations (of forgetfulness). And when Satan comes to one of you and says: 'You have broken your ablution,' let him say (in his heart): 'Kadhabta' (You have lied), unless he perceives a smell with his nose or hears a sound with his ear." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.

It is narrated from Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever makes an oversight in his prayer regarding three or four rak'ahs, let him complete it, for an addition (of a rak'ah) is better than a deficiency." This hadith is mufassar (explanatory) and has a sahih (authentic) chain, but the two Shaykhs did not record it.

It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "There is no consideration of forgetfulness in moving from one posture of the prayer to another, except that he stands up in place of sitting or sits down in place of standing." This hadith has a sahih (authentic) chain, but the two Shaykhs did not record it.

Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates: I was sitting with Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) while he was the Caliph, and he said: "O Ibn Abbas! Have you heard from the Messenger of Allah (peace and blessings be upon him) or from any of his Companions anything mentioning what the Messenger of Allah (peace and blessings be upon him) commanded when a man forgets in his prayer?" I said: "No, O Commander of the Believers! Have you not heard anything either?" He said: "No." Just then Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him) came in to us and asked: "What are you two discussing?" Sayyiduna Umar (may Allah be pleased with him) said: "I asked him whether he has heard anything from the Messenger of Allah (peace and blessings be upon him) or his Companions about the ruling on forgetfulness in prayer." Abd al-Rahman (may Allah be pleased with him) said: "I have knowledge of that." Umar (may Allah be pleased with him) said: "(Tell us,) for you are, in our view, just and well-pleasing." So Abd al-Rahman (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "When one of you is in doubt about two rak'ahs, let him count them as one; when he is in doubt between two and three, let him count them as two; and when he is in doubt between three and four, let him count them as three. Then let him complete the rest of his prayer, so that the doubt falls on the side of addition. Then let him perform two prostrations (of forgetfulness) while sitting, before giving the salam." This hadith is sahih (authentic) on the condition of Imam Muslim, and it is a supporting witness (shahid) for the hadith of Abd al-Rahman bin Thabit bin Thawban mentioned two hadiths before this one.

Abd al-Rahman bin Shumasah al-Mahri narrates: Sayyiduna Uqbah bin Amir al-Juhani (may Allah be pleased with him) led us in prayer, and he stood up (after the second rak'ah) instead of sitting. The people said: "Subhan Allah, Subhan Allah" (Glory be to Allah), but he did not sit and continued standing. Then, when he reached the last part of his prayer, he performed two prostrations of forgetfulness while sitting. After giving the salam he said: "I heard you just now saying 'Subhan Allah' so that I would sit down, but the fact is that the Sunnah is what I did." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.