Musnad Abu Ya'la al-Mawsili 252:43

Harun ibn Ma'ruf narrated to us, Ibn Abi Hazim narrated to us, he said: My father said, from Sahl ibn Sa'd, he said: The Messenger of Allah (may Allah bless him and grant him peace) said: "They will not cease to be in goodness as long as they hasten the breaking of the fast."