Hakam bin al-'Araj reported: I went to Ibn 'Abbas (Allah be Pleased with both of them) and he was reclining using his mantle as a pillow near the fountain of Zamzam. I said to him: Tell me about fasting on Ashura. He said: When you see the new moon of Muharram then count the (days) and observe fast on the 9th. I said to him: Is it how the Messenger of Allah ( صلی اللہ علیہ وسلم ) observed the fast? He said: Yes.

Hakam bin 'Araj reported: I asked Ibn Abbas (RA) as he was reclining using his cloak as a pillow near Zamzam about fasting on 'Ashura. The rest of the hadith is the same.