Is it permissible to say: (If Allah wills) regarding an action that has already been completed?

Q: I have heard some people say: If you have done an action, such as prayer or fasting, or any action in religion or in this world, and you are asked: Did you pray? or Did you fast? do not say "If Allah wills," but rather say "Yes," because you actually did it. What is your opinion?
A: This requires a detailed explanation. As for acts of worship, there is no harm in saying: "If Allah wills, I prayed," or "If Allah wills, I fasted"; because he does not know whether he completed it and it was accepted from him, or not. The believers used to qualify their statements of faith and their fasting with "If Allah wills"; because they did not know whether they had completed them or not, so one of them would say: "I fasted, if Allah wills," and would say: "I am a believer, if Allah wills."
As for a matter that does not require mentioning the will of Allah, such as saying: "I sold it, if Allah wills"—this does not require that. Or if he says: "I had lunch or dinner, if Allah wills," this does not require him to say the phrase "If Allah wills"; because these matters do not require the qualification of Allah's will when reporting about them, because they are ordinary matters that he has done and finished with, unlike matters of worship, where one does not know whether he fulfilled them or shortchanged their right. So if he says "If Allah wills," it is for seeking blessing by His name (Glorified and Exalted is He) and out of caution against claiming something that he had not completed or fulfilled its right.