It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) slept until the sound of his (peace and blessings be upon him) snoring could be heard. He (peace and blessings be upon him) got up, then prayed and did not perform ablution. Ikrimah said: The Prophet (peace and blessings be upon him) was protected.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 599