Musnad Ahmad 31:714

'Affan narrated to us, Hammam narrated to us, Qatadah narrated to us, from Abu Nadrah, from Abu Sa'id al-Khudri, who said: "We went on a military expedition with the Messenger of Allah, may Allah bless him and grant him peace, on the sixteenth of Ramadan. Some of us fasted, and some of us did not fast. The one who fasted did not criticize the one who did not fast, nor did the one who did not fast criticize the one who fasted."