Explanation of Riyad al-Salihin-51a

The Shaykh : The author (may Allah have mercy on him) stated in his book Riyad al-Salihin, quoting from Abu Hurayrah (may Allah be pleased with him), that the Prophet (peace and blessings be upon him and his family) said: And Muslim added: This means that the Prophet (peace and blessings be upon him) commanded a person, when he hears the iqamah while outside the mosque, to come to the mosque, but with calmness and dignity. He should not come running or hurrying in an ugly manner, because he is in prayer. So, if he comes, whatever he catches up with, he should pray, and whatever he misses, he should complete. If you come and the imam is bowing, say the takbir of ihram while standing upright, then bow, and by doing so, you catch up with the rak'ah. If you come and he is standing up from bowing, say the takbir, enter with him, and prostrate with him, but do not count this rak'ah, because if a person does not catch up with the imam’s bowing, he has missed the rak'ah. If you come and he is prostrating, say the takbir of ihram while standing, then prostrate, and do not wait for him to stand up. If you come and he is sitting, say the takbir while standing, then sit. In whatever state you catch up with the imam, do as the imam does. If you come and he is in the final tashahhud, look: if there is a congregation, do not enter with him, because you do not catch up with the congregational prayer by catching up with the tashahhud. You do not catch up with the congregation unless you catch up with a complete rak'ah, based on the saying of the Prophet (peace and blessings be upon him and his family): And if there is no congregation with you, or you cannot catch up with another mosque, enter with him even in the tashahhud, and do not count this as anything, because you missed the bowing. In his saying (peace and blessings be upon him): there is evidence that when the masbuq stands up to make up, he makes up the end of his prayer, not the beginning. So, if he catches up with the last two rak'ahs of the Zuhr prayer, for example, and stands up to make up, the two rak'ahs he makes up are the end of his prayer, so he does not add to al-Fatihah, because it is the sunnah not to add to al-Fatihah in the last two rak'ahs.