Explanation of the author's statement: "If he breaks his vow under compulsion or while forgetting, there is no expiation"

The Shaykh : The author (may Allah have mercy on him) says: "If he breaks his vow under compulsion or while forgetting, there is no expiation" I think the example is clear? We gave an example of this just a moment ago: if he breaks his vow under compulsion or while forgetting, there is no expiation. But when the excuse is gone, if he remains and then breaks his vow, the apparent meaning of the author's words here is that if he breaks his vow while ignorant, he owes the expiation. How can he be ignorant? He says, "By Allah, I will not wear this garment," and then in the morning he wears it, thinking it is another garment, not the one he swore about. Is this ignorance or forgetting?

The questioner : ... .

The Shaykh : Yes, this is ignorance. The apparent meaning of the author's words here is that he owes the expiation, because he did not mention anything except two conditions: that he did it willingly.