Question: Controversy arose among the seekers of religious knowledge, not to mention the masses, regarding observing Sawm (fast) on Friday if it coincides with the Day of `Arafah (9th of Thul-Hijjah). Is it permissible to observe Sawm on the Day of `Arafah alone if it happens to be on a Friday? Or, should a person observe Sawm on a day preceding or succeeding it, bearing in mind that the former case conflicts with the Hadeeth prohibiting the observance of Sawm on Friday alone? We hope that Your Eminence will make this issue clear providing the sound Shar`ee (Islaamic legal) ruling. May Allaah reward you with the best!
Answer: It is permissible to observe Sawm on the Day of `Arafah alone if it happens to be on a Friday without observing Sawm on a day preceding or succeeding it as the Prophet (peace be upon him) is authentically reported to have urged people to observe Sawm on this day highlighting its superiority and the great reward for observing Sawm on it. The Prophet (peace be upon him) said: Fasting the Day of `Arafah forgives the sins of two years: the previous and the following. As for the Day of `Aashoora’ i.e. the tenth of Muharram, it forgives the sins of the previous year. Related by Ahmad, Muslim and Aboo Daawood... read more here.