This is one of the matters in which Hajj is distinct from all other acts of worship. With all other acts of worship, if one renounces them, one exits them; Hajj, however, is not so.
“Expiation for wearing clothing, applying perfume, and covering the head is waived when done forgetfully, …”
His statement, “Expiation for wearing clothing, applying perfume, and covering the head is waived when done forgetfully”: with regard to whether their expiation is waived due to an excuse, prohibited acts fall into two categories:
The first: those whose expiation is waived due to an excuse.
The second: those whose expiation is not waived due to an excuse.
The author says, “is waived when done forgetfully”; the same applies to ignorance and coercion. Thus, if a person forgets and puts on a garment while in ihram, nothing is due from him. However, as soon as he remembers, he must remove it and wear the izār and ridāʾ. The same applies to perfume: if he applies perfume while in ihram out of forgetfulness, nothing is due from him; but once he remembers, he must hasten to wash it off. There is nothing due from him while washing it off, even though he will be touching it, because this contact is for the purpose of removing it, not retaining it. Movement involving something in order to rid oneself of it is not deemed unlawful.
Consider a person who unlawfully usurps some land and resides upon it. Then another man comes to him, admonishes him, and he leaves. He is not held accountable for the time spent walking across that land in order to leave it, because he is moving only to rid himself of the unlawful situation.
But if he gets up and strolls about the land at ease, then he is sinful in doing so, because he has not sought to rid himself of it.
Likewise, when a man cleans himself after relieving himself, and his hand comes into contact with impurity, he is not blamed for that, because he did so only in order to remove it.
The same applies to covering the head: if one forgets and puts on a shirt, he should remove it from above, even if this covers his head, because such covering is only momentary and is done in order to remove the garment.