Amr bin Shu'ayb narrates from his grandfather (may Allah be pleased with him) that in the year of the expedition of Tabuk the Messenger of Allah (peace and blessings be upon him) stood at night in prayer. Then he narrated a long hadith. He (peace and blessings be upon him) said: "Last night I was given five things which were not given to anyone before me. The earth has been made for me a place of prayer and a means of purification; wherever the time of prayer comes upon me, I wipe (with earth) and pray." Then he (peace and blessings be upon him) said: "The fifth thing is that it was said to me: Ask, for every prophet has asked. I have postponed my request until the Day of Resurrection; it will be for you (that is, for the Ummah), and it (the intercession) will be for everyone who bears witness that la ilaha illallah (there is no god but Allah)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1060