His statement, “Whoever vows to fast for a month must fast consecutively,” means that he is required to fast without interruption. A vow to fast a month is of two types:
First: that he vows to fast a particular month, such as Rabīʿ al-Awwal. In this case, he must fast consecutively, because specifying the month necessarily entails this; it is not possible for him to fast it except consecutively.
Second: that he vows to fast an unspecified month, saying, “I vow to Allah that I will fast a month.” The author holds that he must fast consecutively, and this is the position of the school. Some scholars, however, hold that consecutive fasting is not required. This issue applies where he has no particular intention. If he does have an intention, then the ruling is according to what he intended; and if he stipulated a condition, then it is according to what he stipulated. Thus, if he says, “My intention is to fast a consecutive month,” we say: You must fast consecutively. Likewise, if he explicitly stipulates this, saying, “I vow to Allah that I will fast a consecutive month,” then he must fast consecutively.
The correct view regarding the second type is that consecutive fasting is not required. The evidence is that if the word “month,” when used without qualification, inherently entailed consecutive fasting, then Allah’s stipulation of consecutiveness in His saying, “two consecutive months,” would be superfluous and unnecessary. Since Allah stipulated consecutiveness for the two months, we know that the word “month,” when used without qualification, does not entail consecutiveness. This is the correct view. Thus, if a person vows, saying, “If Allah cures my sick person, then I vow to Allah that I will fast a month,” and Allah cures his sick person, we say to him: Fast a month. If he then asks, “Must I fast consecutively?” we say: That is not required of you unless you intended it or stipulated it.
His statement, “must fast consecutively”: is he required to fast thirty days, or is he required to fast only twenty-nine days? We say: If he begins the fast on the first day of the month, he is required to fast only the month, whether it is twenty-nine days