Musnad Ahmad 517:1

Muhammad ibn Ubayd narrated to us, Hashim—meaning Ibn al-Barid—narrated to us, he said: Abdullah ibn Muhammad ibn Aqil narrated to us, from Ibn Jabir, who said: I reached the Messenger of Allah (peace and blessings of Allah be upon him) while he was relieving himself. I said, "Peace be upon you, O Messenger of Allah." He did not return the greeting to me. I said, "Peace be upon you, O Messenger of Allah." He did not return the greeting to me. I said, "Peace be upon you, O Messenger of Allah." He did not return the greeting to me. The Messenger of Allah (peace and blessings of Allah be upon him) went off walking, and I was behind him, until he entered his dwelling, and I entered the mosque. I sat down, sorrowful and sad. Then the Messenger of Allah (peace and blessings of Allah be upon him) came out to me, having purified himself, and said: "Upon you be peace and the mercy of Allah, and upon you be peace and the mercy of Allah, and upon you be peace and the mercy of Allah." Then he said: "Shall I not inform you, O Abdullah ibn Jabir, of the best surah in the Quran?" I said: "Yes, O Messenger of Allah." He said: "Recite 'All praise is due to Allah, Lord of the worlds' until you complete it."