it may be called a shāh. Thus, if someone says, “By Allah, I shall certainly buy a shāh for my guests,” then goes and buys a goat, he has broken his oath, because he has not fulfilled it: in customary usage, shāh means a female sheep.

A second example is dābbah. Linguistically, it refers to everything that moves upon the earth, whether it has two legs or four, or whether it moves upon its belly. The evidence for this is the saying of Allah, Most High:

“And Allah created every creature from water: among them are those that move upon their bellies, among them are those that walk on two legs, and among them are those that walk on four.” [al-Nūr: 45]

Thus, dābbah encompasses everything. Allah, Most High, also says:

“There is no creature on earth but that its provision rests with Allah.” [Hūd: 6]

So what does dābbah mean in customary usage? In one convention, it means four-legged animals; in another, it refers specifically to a donkey. Thus, if someone says, “You are a dābbah,” he means, “You are a donkey.”

Accordingly, an oath is governed by customary usage, because that is the prevailing and commonly understood meaning among ordinary people. When it is the prevailing meaning known to ordinary people, their intention is understood accordingly.

Language, customary usage, and the Sharīʿah may also coincide. When they coincide, the matter is clear; but when they differ, the Sharīʿah takes precedence, then customary usage, then the language.

His words, “If he swears concerning intercourse with his wife or entering a house, his oath relates to intercourse with her and entering the house,” mean, for example, that if a man says, “By Allah, I will not tread upon my wife,” and then goes and has intercourse with her, we say to him, “You have broken your oath.” If he says, “How have I broken my oath, when treading upon her means stepping on her with my feet?!” we say: “But customary usage has prevailed over the linguistic meaning.”