The Book of Faith (Kitab Al-Iman)
Muslim :: Book 1 : Hadith 293
Jabir b. 'Abdullah reported: I heard the Messenger of Allah (may peace be upon him) say: A section of my people will not cease fighting for the Truth and will prevail till the Day of Resurrection. He said: Jesus son of Mary would then descend and their (Muslims') commander would invite him to come and lead them in prayer, but he would say: No, some amongst you are commanders over some (amongst you). This is the honour from Allah for this Ummah.