"There is no fast for the one who did not make it incumbent upon himself from the night before."
Sunan Ibn Majah Book 7, Hadith 63
← Previous Hadith "When any one of you breaks his fast, let him break it with dates. If he cannot find dates, then let him break it with water, for it is a means of purification."

Sunan Ibn Majah Book 7, Hadith 62 Next Hadith → “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.”

Sunan Ibn Majah Book 7, Hadith 64