It is narrated from Kurayb, the freed slave (mawla) of Sayyiduna Ibn Abbas (may Allah be pleased with them both), that Ibn Abbas (may Allah be pleased with them both) and some of the Companions of the Messenger of Allah (peace and blessings be upon him) sent me to Sayyidah Umm Salamah (may Allah be pleased with her) to ask on which days the Messenger of Allah (peace and blessings be upon him) fasted the most. She said: "Saturday and Sunday." I returned and told them, and it was as if they found this strange. Then they all went to her together and said: We sent this messenger to you to ask about such-and-such, and he told us that you said such-and-such. She said: "He has spoken the truth. The Messenger of Allah (peace and blessings be upon him) fasted most on Saturday and Sunday, and he used to say: 'These two days are festival days of the polytheists, and I wish (by fasting) to differ from them.'"