One who has missed a rakah and whom the imam puts forward

Al-Hasan was asked: A man missed one rak'ah and then joined the prayer; the imam's ablution broke, so he took this follower by the hand and put him forward. What should he now do? Al-Hasan said: He should pray one rak'ah and sit, then build on the people's prayer. When he has led them in four rak'ahs, he should sit and recite the tashahhud, then take a man by the hand and put him forward; when that man gives the salam, he should stand up and pray the rak'ah he missed.

Ibrahim was asked about a person whom the imam appointed as his deputy after one rak'ah had passed, while he himself had missed that rak'ah: what should he do? He said: He should lead the people in the rest of the prayer; when he has completed the prayer, he should take hold of a man who prayed that rak'ah and put him forward; when that man gives the salam, he should stand up and complete his own prayer.