BOOK OF FASTING
The fast of Ramadan becomes obligatory either by completing thirty days of Shaʿbān or by sighting the new crescent. One upright witness is sufficient to confirm the sighting, although a secondary opinion requires two. For a single witness to be accepted he must possess the qualities of uprightness; according to the sounder view a slave or a woman may not serve in this capacity. If we begin the fast on the testimony of one upright witness and, after thirty days, do not see the next crescent, we break the fast—this is the preponderant ruling—even when the sky is perfectly clear.
When the crescent is sighted in one town, its ruling applies to the nearby locality but not to a distant one, in the stronger opinion. The distance deemed “remote” is that which permits shortening the prayers. Another view links the matter to differing horizons, and I say that this is the sounder position—Allah knows best.
If a sighting does not bind another town and someone travels from the place where the crescent was seen to that other locality, the preponderant view is that he follows them in finishing the fast. Conversely, a person who travels from the second town to the place of sighting celebrates the Feast of Breaking Fast with them and later makes up one day. Should someone begin the morning celebrating Eid and then sail to a distant land whose inhabitants are still fasting, the sounder view is that he must abstain for the remainder of that day.
Section
Intention is a prerequisite for every fast. For an obligatory fast it must be formed at night, yet the correct view is that it need not be confined to the latter half of the night. Eating or marital relations after forming the intention do not harm it, nor is it necessary to renew the intention after sleep. A voluntary fast is valid when the intention is made before the sun reaches its zenith, and—according to one opinion—even after that, but the stronger position is that the conditions required for fasting must be in place from the very beginning of the day.