Answer
Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Fasting in Rajab is recommended because it is one of the sacred months in Islam. However, no authentic hadith proves that fasting specific days in Rajab carries a special reward. Muslims should observe voluntary fasting without assigning unverified merits.
Stating the reward of observing voluntary fasting in Rajab, Sheikh Atiyyah Saqr, the late head of Al-Azhar Fatwa Committee, states:
Observing voluntary fasting during the sacred months or Al-Ashhur Al-Hurum, including the month of Rajab, is recommended.
Prophet Muhammad (peace be upon him) instructed his Companions to observe voluntary fasting in Al-Ashhur Al-Hurum.
He used to urge his Companions to fast three days of every month.
Thus, fasting in Rajab is recommended but there is no authentic hadith that indicates that fasting certain days of Rajab, for example the first day, entails a special reward.
Allah Almighty knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.