Is it permissible to fast on the thirteenth of Dhu al-Hijjah for one whose habit is to fast on the white days?

Question:
Peace be upon you, Your Eminence, father. The questioner says: The days of Tashreeq are the eleventh, twelfth, and thirteenth. I wish to fast on the white days of the month of Dhu al-Hijjah. Is it permissible for me to fast on the thirteenth day, since it is shared between the days of Tashreeq and the white days?

Answer:
It is not permissible for you, because the white days are days of the festival, and it is not permissible to fast on the day of the festival. In the hadith: regarding blood, a muddah, or a qiran, the one who owes a fidyah and cannot find a fidyah, or the one performing tamattu' or qiran who cannot find the value of the hady, fasts the three days of Tashreeq. As for anyone else, he does not fast, because they are days of the festival. Yes.