Musnad Ahmad 2:290

Hajjaj narrated to us, Laith narrated to us, Bukayr narrated to me, from Abd al-Malik ibn Sa’id al-Ansari, from Jabir ibn Abdullah, from Umar ibn al-Khattab, may Allah be pleased with him, that he said: I felt a desire one day, so I kissed while I was fasting. Then I came to the Messenger of Allah, peace and blessings of Allah be upon him, and said: "I have done a great thing today; I kissed while I was fasting." The Messenger of Allah, peace and blessings of Allah be upon him, said: "What do you think if you were to rinse your mouth with water while you are fasting?" I said: "There is no harm in that." The Messenger of Allah, peace and blessings of Allah be upon him, said: "Then why [are you concerned]?"