It is narrated from Hazrat Anas (may Allah be pleased with him) that once the time for Isha prayer had come, a man came and said, "O Messenger of Allah (peace and blessings be upon him)! I have a task with you." The Prophet (peace and blessings be upon him) began to converse with him alone in the mosque until the people fell asleep. Then the Prophet (peace and blessings be upon him) led the prayer, and the narrator did not mention ablution.