Making up the fast for one whose fast was invalidated by the secret habit and ignorance of the number of days

Question:
Honorable Shaykh, a person was afflicted with the secret habit, and he used to do it at the end of Ramadan for two consecutive years. He knew that it was forbidden, but he did not know that he had erred in his understanding regarding its ruling. Now he has started, and he does not know the number of days on which he erred, but he knows that it was not all the days of the month, of course.

Answer:
He has two obligations. The first is repentance to Allah the Exalted, repenting and not returning to this act, for whoever repents, Allah accepts his repentance. The second is that he must make up the days on which the secret habit occurred, because the fast was invalidated and became void. If he does not know the number of days, he must strive to estimate and be cautious. He should strive, and if he is convinced that it was ten days or fifteen days, he should make it fifteen days, as that is safer. He should fast the greater of the two estimates out of caution.