Musnad Ahmad 1969

It was narrated that Ibn "Abbas said: A woman came to the Prophet (ﷺ) and said: Ö Messenger of Allah, my mother has died and she owed the fasting of one month; can I make it up on her behalf? He said: “Do you think that if your mother owed a debt, would you pay it off?” She said: Of course. He said: "The debt owed to Allah is more deserving of being paid off.”