‘Awf, that the Messenger of Allah (may Allah bless him and grant him peace) said: "If one of you doubts in his prayer and does not know whether he increased or decreased, then if he doubts between one and two, let him treat them as one, so that the uncertainty remains regarding the increase, then let him prostrate twice while sitting before he performs the taslim, then perform the taslim." Reported by al-Athram, Ibn Majah, and al-Tirmidhi, [who said: This is a sound (sahih) hadith] (9). This is because the fundamental principle is the absence of that (10) which he doubted, [so he builds upon its absence, just as if he doubted regarding a bowing (ruku‘) or a prostration (sujud). The first narration is the choice of al-Khiraqi, and it is the famous one from Ahmad; because] (11) 'Abd Allah ibn Mas'ud narrated that the Messenger of Allah (may Allah bless him and grant him peace) said: "If one of you doubts in his prayer, let him exercise personal effort (taharri) to find what is correct, let him complete it based upon that, then let him prostrate twice." Agreed upon (12). And in a narration by al-Bukhari: "After the taslim." And in another phrasing: "Let him consider what is most likely to be correct in that regard." And in another phrasing:
= The hadith is recorded by Muslim, in: Chapter: Oversight in Prayer and Prostrating for it, from the Book of Mosques 1/400. And Abu Dawud, in: Chapter: If One Doubts Between Two and Three, He Who Said One Should Cast Away the Doubt. Sunan Abi Dawud 1/235. And Ibn Majah, in: Chapter: What Has Been Said Regarding One Who Doubts in His Prayer and Returns to Certainty, from the Book of Establishing Prayer. Sunan Ibn Majah 1/382. It was also recorded by al-Nasa'i, in: Chapter: The One Praying Completes According to What He Mentioned When He Doubts, from the Book of Oversight. Al-Mujtaba 3/22, 23. And al-Darimi, in: Chapter: The Man Who Does Not Know Whether He Prayed Three or Four, from the Book of Prayer. Sunan al-Darimi 1/351. And Imam Malik, in: Chapter: The One Praying Completes What He Mentioned When He Doubts in His Prayer, from the Book of the Call to Prayer. Al-Muwatta 1/95. And Imam Ahmad, in: al-Musnad 3/72, 83, 84, 87. (9) Omitted from: M. It was recorded by Ibn Majah, in: Chapter: What Has Been Said Regarding One Who Doubts in His Prayer and Returns to Certainty, from the Book of Establishing Prayer. Sunan Ibn Majah 1/381, 382. And al-Tirmidhi, in: Chapter: What Has Been Said Regarding the Man Who Prays and Doubts Regarding Increase or Decrease, from the Chapters on Prayer. ‘Aridat al-Ahwadhi 2/187. It was also recorded by Imam Ahmad, in: al-Musnad 1/190, 193. (10) In M: "Performing that". (11) In M: "Then he is obligated to perform it, just as if he doubted whether he had prayed or not. Ibn Abi Musa mentioned in al-Irshad, from Ahmad, another narration regarding the one praying alone: that he builds upon his predominant inclination like the Imam. This is the apparent meaning of the speech of Ahmad, may Allah have mercy on him, in the narration of those who said so." (12) Recorded by al-Bukhari, in: Chapter: Facing towards the Qibla wherever one is, from the Book of Prayer, and in: Chapter: If One Breaks an Oath Out of Forgetfulness, from the Book of Oaths. Sahih al-Bukhari 1/111, 8/170. And Muslim, in: Chapter: Oversight in Prayer and Prostrating for it, from the Book of Mosques. Sahih Muslim 1/400. It was also recorded by Abu Dawud, in: Chapter: If He Prays Five, from the Book of Prayer. Sunan Abi Dawud 1/234. And al-Nasa'i, in: Chapter: Personal Effort (Taharri), from the Book of Oversight. Al-Mujtaba 3/23. And Ibn Majah, in: Chapter: What Has Been Said Regarding One Who Doubts in His Prayer and Exercises Personal Effort for What is Correct, from the Book of Establishing Prayer. Sunan Ibn Majah 1/383. And Imam Ahmad, in: al-Musnad 1/379, 438.
