Observing Sawm on Mondays and Thursdays is Nafilah and not Waajib

Question: I like to observe Sawm (Fast) on Mondays and Thursdays because our deeds are presented to Allaah (Glorified be He) on these two days. The Prophet (peace be upon him) stated: These (Monday and Thursday) are two days on which people’s deeds are presented to the Lord of the Worlds, and I want my deeds to be presented when I am observing Sawm.

Is it permissible to observe Sawm of Monday and Thursday of every month? In summer, it is too hot for me to observe Sawm of these two days every week. Should I observe Sawm on them every week in winter? Please advise, may Allaah reward you with the best.

Answer: When the Prophet (peace be upon him) performed any deed, he would do so consistently. However, if there is hardship in observing Sawm on these days, it is permissible for you not to observe their Sawmduring summer and to observe their Sawm in winter because observing Sawm on Monday and Thursday is Nafilah (supererogatory) and not Waajib (obligatory). Whoever observes their Sawm will be rewarded… read more here.