Assalaamu alaykum, Scholar. I have encountered different opinions in regards to obedience to parents in fasting voluntarily, such as shaykh Ibn ‘Uthaymeen saying that is not obligatory, and other scholars as Bin Baaz saying that it is obligatory, and also another scholar saying that the one who fasts against his parents wishes thinks that he is doing good. According to the three conditions of obedience to the parents and the statetemnts of Ibn Taymiyyah, which say: if there is a benefit on the child and no benefit on the parents, no obedience is required, so according to this, it is not obligatory to obey, and after asking a shaykh who told me that it is not obligatory to obey in this, this is what I am doing: my parents only allow me to fast on Mondays and Thursdays and other days such as ‘Aashoorah etc., but I want to fast more, such as the white days, or most of Muharram, as well as other isolated days, because fasting helps me with the permission of Allah in not eating too much during the day, as I am a student of knowledge, and also in obtaining the great reward. However, these last days, doubts have come to me as to whether Im falling into Uqooq (disobedience/undutifulness) or not, as I have heard many scholars say that it is obligatory to obey them. Please scholars, clarify this topic for me.

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

The scholars held different opinions regarding obedience to parents in this situation and similar ones, because setting the determining factor in this regard is problematic. Al-ʻAyni said, "Specifying what requires obligatory obedience to parents and what involves Uqooq to them is a difficult issue." [ʻUmdat Al-Qaari’]

We are inclined to the view of some scholars in that it is obligatory to obey them in what involves benefit to them and does not involve harm to their child, as underlined in fatwa 131695.

Accordingly, if your parents do not have a valid reason for preventing you from fasting on the days which you mentioned, then there is no harm on you to fast; but there is no doubt that it is better to try to convince them and obtain their pleasure, especially given that they allow you to fast on other days, as you mentioned, which shows that they wish well for you.

Allah knows best.