The ruling on breaking a voluntary fast when food is served

Question:
May Allah reward you, Honorable Shaykh. This is a question that its owner described as very important, and that he was entrusted with by another person, who is the questioner. He asks: What is the ruling if a fasting person breaks his fast by mistake while fasting on Monday and Thursday? Also, if a guest comes to him at lunchtime and he is fasting and about to break his fast, what should he do in that case?

Answer:
Regarding voluntary fasting, it is permissible for a person to break it and be patient, especially if there is a reason for it, such as a guest being present, or if he is invited to a wedding feast. In that case, he should break his fast and eat.
This is because completing a voluntary fast is not obligatory. The Prophet (peace and blessings be upon him) broke his voluntary fast. He was fasting a voluntary fast, and when some of his wives informed him that some food had been served to him, he asked for it and ate from it (peace and blessings be upon him). He said, "I have been fasting since morning," but he praised that food and ate from it. This indicates that it is not obligatory to continue with a voluntary fast, nor is it obligatory to complete it. If one breaks it, it is not obligatory to make it up. The matter is broad in this regard. It is only the obligatory fast that is not permissible to break, whether it is the fast of Ramadan, making up a fast from Ramadan, or a fast for expiation. It is not permissible to break an obligatory fast. As for voluntary fasting, it is not permissible to break it, and the person is at ease. Yes.