It is narrated from Sayyiduna Abu Dharr Ghifari (may Allah be pleased with him) that I asked: O Messenger of Allah! How did you come to know and then become certain that you are a Prophet? The Prophet (peace and blessings be upon him) said: "O Abu Dharr! Two angels came to me while I was on the stony ground of Makkah. One of them was coming down to the earth, but the other remained between the earth and the sky. One of them said to his companion: Is he the one? He replied: Yes, he is the one. Then he said: Weigh him against one man. So I was weighed against him and I was heavier. Then the angel said: Now weigh him against ten men. I was weighed against them and I was still heavier. Then he said: Weigh him against a hundred men. So I was weighed against those hundred men and I was heavier than them as well. Then he said: Now weigh him against a thousand men. So I was weighed against them and I was still heavier than them, as if I am seeing them falling from the scale pan." Then the Prophet (peace and blessings be upon him) said: "One of them said to the other: If you weigh him against his entire Ummah, he will still be heavier than them."