Tirmidhi

Explanation:
1:
I say: Allah is Pure, all praise is for Allah, and there is no deity worthy of worship except Allah, and Allah is the Greatest.

Hadith Commentary: Benefits and Issues: From the narration of Aisha radi Allahu anha and Ibn Abbas radi Allahu anhu, it is explicitly established that the guardian (wali) of the deceased may fast on their behalf, and he should do so. The Prophet sallallahu alayhi wa sallam explained this matter by way of an example: when a fast is a right of Allah upon a person, it is in the ruling of a debt. Just as the repayment of a human debt is necessary, even more so is the repayment of Allah’s debt obligatory. And just like Hajj, fasting is also such a right, in which deputization (niyabah) during a person’s lifetime, in case of excuse or necessity, is permissible.

However, deputization in prayer is, by consensus, not permissible.

Therefore, according to the literalists (Ahl al-Zahir), based on the command of the Prophet sallallahu alayhi wa sallam, it is necessary for the wali to fast. The hadith scholars (muhaddithin), Abu Thawr, and some of the Shafi’is, also, on the basis of these authentic ahadith, have declared it permissible. And this is also the opinion of Imam Ibn Taymiyyah rahimahullah, and Hafiz Ibn Hazm rahimahullah has strongly advocated for it. However, the Hanafis and Shafi’is, who, by analogy (qiyas), even in acts of worship (i.e., bodily acts of worship), consider the recitation of the Qur’an on behalf of the deceased permissible—although there is no mention of this in any hadith, and it is a purely bodily act of worship like prayer, in which deputization is not established from the Prophet sallallahu alayhi wa sallam—according to them, the wali cannot fast on behalf of the deceased. And in opposition to the authentic ahadith, they present the statements of the Companions radi Allahu anhum ajma’in, or such rules and regulations which are either constructed or not applicable.

In any case, according to Imam Abu Hanifah rahimahullah and Imam Malik rahimahullah, if the deceased made a bequest (wasiyyah) for the payment of fidyah from his wealth, then it is obligatory to pay the fidyah. If no bequest was made, then it is recommended (mustahabb).

According to Imam Ahmad rahimahullah and Ishaq rahimahullah, in the case of a vowed fast (nadhar), the fasts should be observed, and in the case of Ramadan, as per Imam Shafi’i rahimahullah, for each missed fast, a poor person should be fed.

Allamah Sindhi rahimahullah has given preference to the apparent (zahir) meaning.