Musnad Abu Ya'la al-Mawsili 115:334

Abu Musa narrated to us, Mu'adh ibn Mu'adh narrated to us, Sa'id narrated to us, from Qatadah, from Anas, from Abu Talhah, who said: When the Messenger of Allah (may Allah bless him and grant him peace) would overcome a people, he liked to stay in their territory for three [days].