It is narrated from Sayyiduna Abdullah bin Ja'far (may Allah be pleased with them both) that when the Messenger of Allah (peace and blessings be upon him) announced the deaths of the people of Mu'tah, he said: "Then one of the swords of Allah, Khalid bin al-Walid, took up the banner, and Allah granted victory at his hands."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3784