Is it good to fast every day?

Scholars differ on the ruling concerning perpetual fasting (fasting the entire year) into two opinions:

The first opinion: Perpetual fasting is absolutely prohibited, either as a matter of disfavor (makrooh), which is the madhhab of the Hanafis and the choice of Ibn Qudamah, Ibn Taymiyyah, and the Permanent Committee, or as a matter of prohibition (haram), as held by Ibn Hazm. They cite as evidence the hadith: "(There is) no fasting for one who fasts perpetually," and the hadith of Anas concerning the Prophet’s (peace be upon him) prohibition of perpetual fasting, and the hadith of Umar: "He neither fasted nor broke his fast," and the hadith of Abdullah ibn Amr: "Fast and break your fast." Those who oppose this view respond to these proofs by stating that perpetual fasting refers to fasting on days that are prohibited for fasting, or that the fasting person becomes accustomed to fasting and does not find it difficult, or that the prohibition is specific to those who are harmed by fasting or neglect a right due to it.

The second opinion: Perpetual fasting is commendable (mustahabb), which is the view of the Malikis, Shafi'is, and Hanbalis, provided that it does not lead to neglect of rights or harm to the fasting person. They cite as evidence the general verses and hadiths indicating the virtue of worship, and the hadith: "Whoever fasts perpetually, Hellfire will be constricted for him," and the hadith of Hamza ibn Amr Al-Aslami and the Prophet's (peace be upon him) approval of his continuous fasting, and what has been reported from some Companions like Ibn Umar, Aisha, and Abu Talha regarding their fasting. Their evidence is countered by stating that the generality of virtues does not specifically apply to perpetual fasting, and the hadith ("Hellfire will be constricted for him") is weak, and continuous fasting does not necessarily mean perpetual fasting.

In conclusion: The opinion that perpetual fasting is disfavored and prohibited is preferred due to the strength and clarity of its evidence, whereas the evidence for the other opinion lacks explicit indication and has been addressed by scholars.