“It is that which is intended to be binding with respect to a possible future matter.” This comprises three conditions:
First: the intention to make it binding.
Second: that it concern the future.
Third: that it concern something possible.
His statement, “the intention to make it binding,” indicates that the one swearing must be someone capable of intent. If he has no intent, his oath carries no legal weight. Thus, if an insane person were to swear an oath a thousand times, his oath would not be binding, because he has no intent. The same applies to one whose mind has deteriorated with old age: his oath is not binding, because he has no intent. Likewise, the oath of an intoxicated person, and of one overcome by intense anger, is not binding, because neither has intent. The oath of a child below the age of discernment is likewise not binding.
If, however, he has reached the age of discernment but not puberty, the apparent meaning of the author’s words is that his oath is binding, because he possesses sound intent. For this reason, the jurists stated that the ritual slaughter of a discerning child is valid, because he has sound intent. They also stated in the chapter on ilāʾ that it is valid when undertaken by a discerning child. This is one of the two narrations in the school of Imam Ahmad. The second view—and the authoritative position of the school—is that it is valid only from one legally accountable.
As for those who maintain that discernment is sufficient, they cite the saying of Allah Most High: “But He will hold you accountable for the oaths you have deliberately sworn.” [al-Ma'idah 5:89] And His saying: “But He will hold you accountable for what your hearts have earned.” [al-Baqarah 2:225] They say: These texts are general, and this is an oath. Its being binding, and the violation of it, do not fall under the category of prescriptive rulings; rather, they fall under the category of declaratory rulings—that is, it is a cause assigned to a legal consequence. Thus, if a child kills someone, expiation becomes due from him; and if he violates an oath, expiation becomes due from him.