If he says, “By Allah, I shall tread upon my wife,” and his wife says to him, “You have done nothing,” whereupon he replies, “Did I not tread on your foot?”—we say: he has not fulfilled his oath, because the ruling relates to sexual intercourse. The literal meaning—treading with one’s foot—has been abandoned, and customary usage has made “treading upon one’s wife” mean having intercourse with her.
To tread upon a house means to enter it, and this apparently applies even in the Arabic language, since it is impossible for a person to tread upon an entire house with his foot: a house is larger than a foot. Thus, if someone says, “By Allah, I shall not tread upon this house,” then enters it, he has broken his oath.
If he enters it while being carried, he has likewise broken his oath. If he had a particular intention, however, that is another matter. But if he had no specific intention, we say: if you enter it—whether you enter on your feet, while being carried, or in any other manner—you have broken your oath, because this is what “treading upon a house” means. This is well known among people: one may say, “By Allah, I shall not set foot in this place,” “By Allah, I shall not set foot in so-and-so’s house,” or “By Allah, I shall not set foot in so-and-so’s shop,” and the matter hinges upon entering it.
If he swears that he will not eat something, then eats it after it has been absorbed into something else—for example, if he swears that he will not eat clarified butter, then eats a sweet dish containing clarified butter whose taste is not perceptible; or swears that he will not eat eggs, then eats a confection made with eggs—he has not broken his oath. But if the taste of any part of that which he swore not to consume is perceptible, he has broken his oath.
His words, “If he swears that he will not eat something, then eats it after it has been absorbed into something else,” mean that he has not broken his oath. This is of great benefit. If he says, “By Allah, I shall not eat this thing,” and that thing is mixed into something else, but is absorbed and disappears, leaving no trace, taste, smell, or effect, then he has not broken his oath. For example, it may constitute one part in a hundred, two parts in a hundred, three parts in a hundred, or the like, such that it has no effect; in that case, he has not broken his oath. Suppose that he says, “By Allah, I shall not drink this thing,” then mixes it with water, and it disappears