It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that the Isha prayer was called to begin, and a man stood up and said: O Messenger of Allah, I have a need. He (peace and blessings be upon him) stood speaking privately with him until the people, or some of them, dozed off; then he (peace and blessings be upon him) led them in prayer and did not perform ablution.
(b) In Sahih Muslim the words 'and he did not mention ablution' are not present.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 593