Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: The first thing I came to know about the affair of the Messenger of Allah (peace and blessings be upon him) was this: I came to Makkah with some of my paternal uncles, and we were directed to Abbas bin Abd al-Muttalib. We reached him while he was sitting by Zamzam, and we sat down with him. While we were with him, a man came from the direction of Bab al-Safa: fair-skinned with a reddish tinge, with thick curly hair reaching halfway down his ears, a high nose, the bridge of his nose raised and its tip small, gleaming front teeth, deep black eyes, a thick beard, a fine line of hair on the chest, sturdy hands and feet, wearing two white garments, as though he were the moon on the night of the full moon. On his right walked a handsome young boy who was near puberty or had reached it, and behind them walked a woman who had covered her adornment. Then he went towards the Black Stone and touched it (istilam), then the boy touched it, then the woman touched it. Then he circled the House seven times, and the boy and the woman circled with him. Then he touched the Corner (the Black Stone), raised his hands and said the takbir, and the boy stood on his right and raised his hands, and the woman stood behind them both, raised her hands and said the takbir. Then he stood for a long time, then he bowed and prolonged the bowing, then he raised his head from the bowing and made qunut while standing, then he prostrated, and the boy and the woman prostrated with him; the two of them did as he did and followed him. (Sayyiduna Abdullah (may Allah be pleased with him)) said: We saw something we had never known in Makkah, and we found it strange. We turned to Abbas and said: "O Abu al-Fadl! We never knew this religion among you. Has something new happened?" He said: "Yes, by Allah! Do you not recognise him?" We said: "No." He said: "This is my nephew, Muhammad bin Abdullah; the boy is Ali bin Abi Talib; and the woman is Khadijah bint Khuwaylid. Listen! By Allah, there is no one on the face of the earth who worships Allah according to this religion except these three."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10359