Sulayman bin Buraydah narrates from his father that on the day of the Conquest of Makkah the Prophet (peace and blessings be upon him) performed all the prayers with a single ablution and wiped over his leather socks. Sayyiduna Umar (may Allah be pleased with him) said: I saw that you (peace and blessings be upon him) did something today that you never did before? He (peace and blessings be upon him) said: "O Umar, I did it deliberately."
(b) Imam al-Shafi'i (may Allah have mercy on him) says that in this hadith there is evidence that whoever rises from sleep should perform ablution.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 574