Can one make up a voluntary fast by intending to complete the remainder of the day after eating or drinking?
General Chapter
Al-Mughni
Book of Fasting
Primary text
Yes, if one intends to fast a voluntary fast, completing the remainder of the day after eating or drinking is permissible. This is deduced from the command given on Ashura: "Whoever woke up having eaten, let him fast the remainder of his day." The act of abstaining for the rest of the day after eating is deemed a fast only metaphorically (tajawwuz), not a legally prescribed fast, as the command did not differentiate between eating or other forms of breaking the fast.
Supporting text
The difference between voluntary and obligatory fasts concerning intention timing is that a voluntary fast permits completion of the remainder of the day even if the beginning was not intended from the night. The obligation for the obligatory fast covers the entire day, requiring prior intention; the allowance for the voluntary fast is to encourage its performance, similar to leniency regarding performing the night vigil or facing the Qibla while traveling.