Catching up with the ma'mum by catching the ruku'

The second question in the letter of the brother (M. R. 'Abd al-Rabb) from Democratic Yemen says: What is the ruling on one who catches up with the imam while he is bowing? Did he catch up with the prayer or not? Because the Prophet (peace and blessings be upon him) said: "There is no prayer for one who does not recite the opening of the Book." Please inform us, may Allah reward you?
Answer: The correct view is that if one catches up with the ruku', he has caught up with the rak'ah. This is because when Abu Bakrah al-Thaqafi entered while the Prophet (peace and blessings be upon him) was bowing, he bowed with him outside the row, then entered the row. The Prophet (peace and blessings be upon him) said to him: "May Allah increase you in eagerness, and do not do it again". He did not order him to make up the rak'ah, which indicates that he is excused. This specifies the statement of the Prophet (peace and blessings be upon him): "There is no prayer for one who does not recite the opening of the Book". This applies to the imam and the one praying alone, and to the ma'mum who is able, according to the correct view. As for the ma'mum who is unable, who came and missed his standing while the imam was bowing, the correct view is that the ruku' suffices for him and his rak'ah is completed. This is the view of the four imams: Abu Hanifah, Malik, al-Shafi'i, and Ahmad, and the majority of the scholars. Some scholars held that it does not suffice and that he must make it up, but the correct view is that it suffices for him. This is the stronger position, and by this he is excused because he did not catch up with the standing. Likewise, if he forgot and did not recite it, or left it off by following some scholars who say that it is not obligatory for the ma'mum, then his prayer is valid. Yes.