Answered by: Shaykh Mustafa Umar
There are some ahadith about performing hijamah (blood-cupping) on the 17th, 19th, and 21st of the lunar calendar. There are also some narrations that say not to do hijamah on specific days like Wednesday and Saturday. What if the two overlap? Are these narrations authentic?
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Most Gracious, the Most Merciful
Both of these reports exist. Here are some of them:
“The Prophet used to like cupping done on the 17th, 19th, and 21st [of the month].”
“The Prophet would get cupped in his jugular veins and his upper back. And he would get cupped on the seventeenth (of the month), (or) the nineteenth, and (or) the twenty-first.”
“She [a woman] said that her father used to forbid his family to have themselves cupped on a Tuesday, and used to assert on the authority of the Messenger of Allah, that Tuesday is the day of blood in which there is an hour when it does not stop.”
Mulla Ali Qari has stated that it is possible to reconcile these, and other narrations, of Ahadith by saying that the specific days which were discouraged to be cupped do not apply when they happen to fall on one of the days when it is recommended to be cupped, such as the 17th, 19th, and the 21st.
Therefore, the recommended days override the discouraging days when they overlap. There is another explanation that the ‘day of blood’ refers to the day that one of Adam’s sons killed his brother, so it is referring to that. There are other theories that have been put forward to reconcile these hadith.
The reports that specify timing for hijamah [cupping] have been disputed by scholars, some considering there are authentic narrations while others saying none of them are strong enough to act upon.
If you choose to be on the safe side, avoid the days that were discouraged when possible.
Only Allah knows best
Written by Shaykh Mustafa Umar
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 [Mishkat Al-Masabih #4547]
 [Tirmidhi #2189]
 [Abu Dawud #3862]
 Mirqat al-Mafatih Sharh Mishkah Al-Masabih, 7:876-877, Darul Fikr, 2002
 Al-Mawdu`at by Ibn al-Jawzi 3:215