If a person breaks his fast during voluntary fasting, is it obligatory for him to make up the fast or not?

Question:
On one day, I decided to fast one day of the week, and in the morning I found that I had broken my fast, so I did not complete the fast for that day. Knowing that my fast was voluntary, is it obligatory for me to repeat the fast for that day? May Allah reward you with good.

Answer:
In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, Lord of the worlds, and may Allah send prayers and blessings upon our Prophet Muhammad, and upon his family and all his Companions. As for what follows, it is not obligatory for a person to complete a voluntary fast; he may break his fast and stop fasting, but completing it is better. However, if he breaks his fast, there is no harm in that; because it is a voluntary fast, not an obligatory one. The Prophet (peace and blessings be upon him) said, meaning: The one who is fasting is the master of his own self, meaning in voluntary fasting. Likewise, if a person is invited by his brother to a wedding feast, he should accept the invitation; if he wishes, he eats, and if he wishes, he declines, so he has the choice, as that came in the hadith from the Prophet (peace and blessings be upon him), Good.
And if he breaks his fast, he is not required to make up this day; because it was not obligatory upon him by the original law, and it was not obligatory upon him by starting it either; rather, it remains a voluntary act whether he completed it or not.