1701. Sunan Ibn Majah Chapter: What was narrated concerning the virtues of fasting; Book 7, Hadith 64

It was
narrated that ‘Aishah said: “The Messenger of Allah (ﷺ)
would
enter upon me and say: ‘Do you have anything (any food)?’ If we
said: ‘No,’ he would say: ‘Then I am fasting.’ So he would
continue
fasting, then it we were given some food, he would break his
fast.”
She said: “Sometimes he would fast and (then) break fast
(i.e.,
combine fasting and breaking fast in one day).” I said: “How
is that?”
She said: “Like the one who goes out with charity
(i.e., something to
give in charity),and he gives some away and keeps
some.”