الكافي- ط الاسلامية, volume 3, page 353

6. Ali ibn Ibrahim has narrated from his father from Ibn Abi ‘Umayr from certain persons of his people who has said the following: “Abu ‘Abdullah (a.s.), about the case of one who performs Salah (prayer) and doubts if he has prayed two, three, or four Rak‘ah, has said, ‘ He stands up and performs two Rak’ah in a standing position. He then says the phrase of offering greeting of peace, then performs two Rak’ah in a sitting position, and says the phrase of offering greeting of peace. If, in fact, they were four Rak’ah the two Rak’ah become optional; otherwise, they complete the four Rak’ah.’”

Translation: Muhammad Sarwar — attributed by Thaqalayn·The Arabic above is the original.

7. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from af-Husayn ibn Sa‘id from Fadalah ibn Ayyub from Aban from ‘Abd al-Rahman ibn Sayabah and abu al-‘Abbas who has said the following: “Abu ‘Abdullah (a.s.), has said, ‘If you do not know whether you have performed three or four Rak’ah and your thought settles on three, then consider it three. If your thought settles on four, say Salam (the phrase of offering greeting of peace) and end Salah (prayer). If your guess is equal; end Salah (prayer), then perform two Rak’ah in a sitting position.’”

Translation: Muhammad Sarwar — attributed by Thaqalayn·The Arabic above is the original.

8. Ali ibn Ibrahim has narrated from his father from Ibn Abi ‘Umayr from Hammad ibn ‘Uthman from al-Halabiy who has said the following: “Abu ‘Abdullah (a.s.), has said, ‘ You may not know whether you have performed two or four Rak’ah and your guess about one side is not greater than the other side. You must say Tashahhud (testimonies of belief) and Salam (the phrase of offering greeting of peace), then perform two Rak’ah and four Sujud (prostrations). Read in them ‘ Umm al-Quran, then say Tashahhud (testimonies of belief) and Salam (the phrase of offering greeting of peace). If, in fact, you had performed two Rak’ah these two complete the four and if, in fact, you had performed four, these two become optional. If you do not know whether you have performed three or four Rak’ah and your guess about one side is not greater than the other; say Salam (the phrase of offering greeting of peace), then perform two Rak’ah in a sitting position. Read in them al-Fatihah al-Kitab. If your guess about three is greater, then perform the fourth Rak’ah. Do not perform two Sajdah (prostration) because of mistake. If your guess about four is greater; say Tashahhud (testimonies of belief) and Salam (the phrase of offering greeting of peace) then perform two Sajdah (prostration) because of mistake.’”

Translation: Muhammad Sarwar — attributed by Thaqalayn·The Arabic above is the original.

9. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Ali ibn Hadid from Jamil certain persons of our people who have said the following: “Abu ‘Abdullah (a.s.), has said, ‘ One may not know whether he has performed three or four and his guess about both sides is equal. (For such case) he (the narrator) has said that he (the Imam) said, ‘If his guess is equal about three and four, he has the choice to perform one Rak’ah standing or two Rak’ah in a sitting position and four Sujud (prostrations) in a sitting position.’ He (the Imam) (a.s.), about a man who does not know if he has performed two or four Rak’ah and his guess about four is greater or about two Rak‘at, he (the Imam) said that he performs two Rak‘at and four Sujud (prostrations). He (the Imam) said, ‘If your guess about two Rak‘at and four is equal, then this and the case of doubt about whether it is three or four Rak‘at is not the same.”’

Translation: Muhammad Sarwar — attributed by Thaqalayn·The Arabic above is the original.