Musannaf Ibn Abi Shayba 4:123

Muhammad ibn Bishr al-‘Abdi narrated to us, from Sa‘id, from Qatadah, from Abu Nadrah, from Abu Sa‘id, who said: We went out with the Prophet of Allah, may Allah bless him and grant him peace, to Hunayn when twelve days of Ramadan remained. A group of the companions of Muhammad fasted, and others broke their fast, and neither found fault with the other.