Musannaf Ibn Abi Shayba 3:2198

Abu Khalid al-Ahmar narrated to us, from Hajjaj, from Abu Ishaq, from al-Harith, from Ali, who said: If a person in a state of major ritual impurity (junub) leads the people in prayer and completes the prayer with them, he ordered him to perform ghusl and repeat [the prayer], but he did not order them to repeat [it].