The inquirer asks, “A group of people entered the mosque at the time of prayer and found the imam and the congregation bowing. If they join the prayer and catch the imam in this prayer position, would they attain that rak‘ah, or must they recite Al-Fatihah before bowing?”

It is established in the four schools of Islamic jurisprudence that if a person praying in congregation joins the imam while he is in ruku‘ (bowing) and bows before the imam rises, that rak‘ah (unit of prayer) counts for him. This is based on the hadith of Ibn ‘Umar (may Allah be pleased with them both) who said, “If you join the imam while he is bowing and bow before he rises, you have attained the rak‘ah. But if he rises before you bow, then you have missed it” (recorded by ‘Abd al-Razzaq in Al-Musannaf).

Based on the above and in reference to the question, those who entered the mosque while the imam was in ruku’, joined him in prayer, and bowed with him are considered to have attained that rak’ah.

And Allah Almighty knows best.