What is the ruling on joining the prayer row (saff) after beginning the bowing (ruku) outside the row, as exemplified by Abu Bakra's case?
Chapter on Imamate and Congregational Prayer
Al-Mughni
Book of Prayer
Primary text
If someone bows before reaching the row and then enters it, there are three states. If he completes a full rak'ah while not in the row, his prayer is invalid based on the Prophet's saying: "There is no prayer for an individual behind the row." If he crawls bowing until he joins the row before the Imam raises his head from ruku, or if another person joins him in bowing before the Imam raises his head, his prayer is valid because he attained the part of the rak'ah with the Imam while in the row. Those who permitted bowing short of the row include Zayd ibn Thabit, Ibn Mas'ud, Zayd ibn Wahb, Abu Bakr ibn Abd al-Rahman, Urwah, Sa'id ibn Jubayr, and Ibn Jurayj. Al-Zuhri, Al-Awza'i, Malik, and Al-Shafi'i permitted it if he was close to the row.
Supporting text
The third state is when he raises his head from ruku and then joins the row, or another person joins him before completing the rak'ah. If someone commits this act while ignorant of its prohibition, his prayer is valid; if he knew, it is invalid, which aligns with the position of Imam Ahmad in one narration. This is the Madhhab of Malik, Al-Shafi'i, and the Companions of Opinion (Ahl al-Ra'y). This ruling is supported by the Hadith of Abu Bakra, who bowed before reaching the row, and the Prophet (PBUH) told him, "May Allah increase your zeal, but do not repeat it." The command not to repeat implies invalidity, yet the Prophet did not order him to repeat the prayer, attributing the act to zeal, not negligence.