him) said: If a person who is junub leads the people in prayer and completes the prayer, I would tell him to do ghusl and repeat the prayer but I would not tell them to repeat it. It was narrated that Ibn 'Umar (may Allaah be pleased with him) led them in praying Fajr, then he said that he had prayed without wudoo', so he repeated it but they did not repeat it. All these incidents were narrated by al-Athram. End quote from al-Mughni (1/419). The Standing Committee for Issuing Fatwas was asked about a man who prayed Zuhr and 'Asr as an imam when he was junub, but he did not know that he was junub. They replied: You have to repeat Zuhr and 'Asr after doing ghusl to cleanse yourself of janaabah, and you must hasten to do that. As for those who offered these prayers behind you, they do not have to repeat them, because 'Umar (may Allaah be pleased with him) led the people in praying Fajr when he was junub and had forgotten about it, so he repeated Fajr but he did not tell those who had offered that prayer behind him to repeat it. And they are excused because they did not know that you did not have wudoo'. End quote.