Hakam bin A'raj says that once I presented myself before Sayyiduna Ibn Abbas (may Allah be pleased with them both), he was sitting leaning against the well of Zamzam, I also went and sat with him, he was the best companion. I asked him to tell me something about the Day of Ashura. He said: In what regard do you want to ask about it? I said: Regarding fasting, that is, on which day should I fast? He said: When you see the crescent of Muharram, keep counting its dates, and when the morning of the ninth day comes, then fast. I asked: Did the Prophet (peace and blessings be upon him) fast in this way? He said: Yes.