His statement, “when he resolves to do so,” means: when he resolves to have intercourse, we say: You may not have intercourse until you make expiation by freeing a slave. If he cannot find one, then he must fast; and if he is unable to fast, then he must feed the poor.
If someone were to ask: What is the wisdom behind the fact that, among all expiations, this particular expiation must be performed before the violation occurs?
The answer is that ẓihār is an abhorrent and false statement; it is therefore grave and repugnant. Thus, the person is dealt with more strictly in this matter. Moreover, were he to have intercourse before making expiation, he would be likely to treat its discharge lightly and delay it. He is therefore barred from this wife until he makes expiation.
His statement, “A single expiation is required if he repeats it concerning one woman before making expiation”: if ẓihār is repeated, is the expiation likewise repeated or not? That is, if he says, “You are to me like my mother’s back,” then says again, “You are to me like my mother’s back,” and then says once more, “You are to me like my mother’s back,” are multiple expiations required, or is only one expiation binding upon him? There is some detail to this. If he made expiation for the first statement and then repeated ẓihār, the expiation is repeated, because this ẓihār is distinct from the first; and because it occurred when his liability had been cleared of the first ẓihār. He must therefore make expiation again.
But if he did not make expiation for the first, then one expiation suffices, because the woman subjected to ẓihār is one and the same, and thus the subject matter is one. This is like a person who swears several oaths concerning one matter—for example, he says, “By Allah, I will not enter so-and-so’s house,” then says a second time, “By Allah, I will not enter so-and-so’s house,” and then says a third time, “By Allah, I will not enter so-and-so’s house.” If he then enters it, only one expiation is required of him, because the matter sworn about is one. Likewise here, the woman subjected to ẓihār is one, so only one expiation is binding upon him.