Is making the intention for a voluntary fast permissible during the daytime?
General Chapter
Al-Mughni
Book of Fasting
Primary text
The intention for a voluntary fast is permissible to be made during the daylight hours. This view is held by Imam Ahmad, Abu Hanifa, and Al-Shafi'i, and is narrated from Abu al-Darda', Abu Talha, Ibn Mas'ud, Hudhayfah, Sa'id ibn al-Musayyib, Sa'id ibn Jubayr, Al-Nakha'i, and the Companions of opinion (Ahl al-Ra'y). The evidence supporting this is the narration from 'A'ishah, may Allah be pleased with her, where the Prophet, peace be upon him, found nothing to eat and declared, "Then I am fasting." This is reported by Muslim, Abu Dawud, and Al-Nasa'i. The fast on Ashura also supports this.
Supporting text
Malik and Dawud hold that the fast is invalid unless the intention is made from the night, citing the hadith, "There is no fast for one who does not intend to fast from the night." They also reason that since the intention for obligatory and voluntary prayer shares the same time frame, so too should fasting.