What is the ruling on fasting on the days of tashreeq (the 11th, 12th, and 13th of Thul-Hijjah)? I made up for missed fasts from Ramadan on the days of tashreeq, but when I did so, I was not aware that fasting on these days is prohibited as I believed that the prohibition was specific to the day of eid Al-Fitr and the day of eid Al-Adh-ha only. Should I fast those days anew?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

The preponderant view among the Muslim scholars is that it is not permissible for a Muslim to fast on the days of tashreeq unless he is engaging in tamattu' Hajj and cannot afford to buy a sacrificial animal. Also, you are not allowed to make up for the fasts that you missed in Ramadan on the days of tashreeq since the only fasting permitted on those days is that prescribed for the one performing tamattu’, as just mentioned.

Also, it is not permissible to fast on the eid days because the Prophet, sallallaahu ‘alayhi wa sallam , said: “No fasting is allowed on the two eids of Al-Fitr and Al-Adh-ha.” [Al-Bukhari and others] Thus, you are not allowed to make up for missed obligatory fasts on those days. This is because when something is forbidden by the sharia, that means that it is not valid and will not be accepted if done.

Allaah Knows best.