Hakam bin A'raj narrates: I went to the service of Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) while he was sitting by the well of Zamzam, leaning against his cloak. I sat down beside him; he was a very excellent companion. I asked him about Ashura: so he sat up straight. Then he asked: Do you want to ask about it in any particular regard? I asked: About its fasting—on which day should we fast? He said: When you see the crescent of Muharram, start counting, then fast on the ninth day. I asked: Did Sayyiduna Muhammad (peace and blessings be upon him) also fast like this? He replied: Yes.