nothing is binding upon him, neither expiation nor anything else; because the time has not elapsed, so he resembles (12) the patient during the month of Ramadan. If his inability continues until it is no longer hoped to be removed, he moves to the expiation and the ransom, according to the disagreement we have mentioned regarding it. If the inability, for which removal is hoped, relates to a specific fast whose time has elapsed, he waits for the possibility to perform it. And is he bound by an expiation for the time elapsing? There are two narrations, which Abu al-Khattab mentioned. One of them: the expiation becomes mandatory; because he failed to perform what he vowed as intended, so the expiation became binding upon him, as if he had vowed to walk to the Sacred House of God and was unable. And because a vow is like an oath; if one swore that he would definitely fast this month, and then broke the fast (13) due to an excuse, an expiation would be binding upon him, so it is the same here. The second: it is not binding upon him; because he performed the fasting that sufficed for his vow without any negligence on his part (14), so no oath expiation is binding upon him (14), just as if he had fasted what he had specified.

Section: If he vowed something other than fasting and was unable to perform it, such as prayer or the like, there is nothing upon him except the expiation; because the Sharia has not provided a substitute for it to which one may turn, so the expiation became mandatory due to his violation of his vow only. If he was unable to perform it due to an incidental cause, its ruling is the same as that of fasting in all the details we have clarified.

1855 - Issue; He said: (And if one vows to fast and does not mention a number, and did not intend it, then the minimum of that is the fasting of one day, and the minimum for prayer is two units [Rak'ahs]).

As for when one vows to fast absolutely, the minimum of that (1) is the fasting of one day; there is no disagreement regarding this, because there is no single, individual fast in the Sharia less than a day, so it is binding upon him (2) because it is the certainty. As for prayer, there are two narrations regarding it. One of them: one unit suffices him. Isma'il ibn Sa'id transmitted it, because the minimum of prayer is one unit, for the Witr is a prescribed prayer, and it is a single unit. It was narrated from Umar, may God be pleased with him, that he performed a voluntary prayer of a single unit (3). The second: only two units suffice him. Abu Hanifa held this view as well, because the minimum of a prayer that is obligatory.