Question: People here differed regarding observing Sawm (Fast) on the Day of `Arafah (9th of Thul-Hijjah) this year as it coincides with Saturday. Some said they observed Sawm on the Day of `Arafah because it was the Day of `Arafah not because it was Saturday on which observance of Sawm is prohibited. Others did not observe Sawm because it was Saturday, the Jews’ day of worship, and they wanted to act in contradiction to the Jews. As for myself, I was of the latter opinion. I am confused as to what the Shar`ee (Islaamic legal) ruling is on this issue. I researched it in many religious and Sharee`ah books; however, I did not reach a decisive ruling on observing Sawm on such a day. I hope that Your Honor will guide me to the Shar`ee ruling and send it me in a written document. May Allaah reward you for this in this life and the Hereafter and for the beneficial knowledge you give to all Muslims.
Answer: Observing Sawm on the Day of `Arafah on its own, whether it coincides with Saturday or otherwise, is permissible. In fact, coincidence with any day of the week will make no difference in this regard, as observing Sawm on the Day of `Arafah is an independent Sunnah (supererogatory act of worship following the example of the Prophet). Moreover, the Hadeeth prohibiting observing Sawm on Saturday is Da`eef (a Hadeeth that fails to reach the status of Hasan, due to a weakness in the chain of narration or one of the narrators) as it is Hadeeth Mudtarib (a Hadeeth with disagreement over a transmitter or the text) that conflicts with authentic Hadeeth... read more here.