What is the ruling on the prayer of the Imam and the congregants if the Imam did not wash one of his feet during ablution?

The Imam's ablution is invalid because he did not wash one of his feet, which is an obligatory part of ablution. Therefore, his prayer is invalid, and he must repeat it, based on the hadith where the Prophet, peace and blessings be upon him, saw a man praying and there was a dry spot on the top of his foot that water had not reached, so he commanded him to repeat his ablution and prayer. As for the congregants, their prayer is valid, and they are not required to repeat it if they were unaware of the invalidity of the Imam's ablution. However, whoever among them was aware of this, their prayer is invalid, and they must repeat it.