Musnad Ahmad 775:0

Narrated by Abdullah ibn Abi Awfa: The Messenger of Allah (peace be upon him) said: "O people, do not wish to meet the enemy, and ask Allah for well-being. But when you meet them, then be patient, and know that Paradise is under the shadows of the swords." Then he said: "O Allah, Revealer of the Book, Mover of the clouds, and Defeater of the Confederates, defeat them and grant us victory over them."