Musnad Ahmad 30:1594

Abu Ja'far narrated to us, 'Abbad ibn al-'Awwam informed us, from Hisham ibn Hassan, from Muhammad ibn Sirin, from Abu Hurayrah, who said: The Messenger of Allah, may Allah bless him and grant him peace, said: "The five prayers, and Friday to Friday, are expiations for what is between them, as long as the major sins are avoided."