The Messenger of Allah ﷺ said, regarding the story of the Battle of Mutah, "Then Khalid bin Walid took up the banner, though he was not among the appointed commanders. He took command on his own initiative."The Messenger of Allah ﷺ then raised his two fingers and said, "O Allah, he is a sword from among Your swords, so grant him victory."
أن رسول الله ﷺ قال- في قصة غزوة مؤته-: ثم أخذ اللواء خالد بن الوليد، ولم يكن من الأمراء هو أمر نفسه فرفع رسول الله ﷺ أصبعيه وقال: اللهم هو سيف من سيوفك فانصره.
Narrated by Nasai (8159) and Ahmad (22551), and Ibn Hibban graded it sahih (7048), all of them through routes from Aswad bin Shayban, from Khalid bin Samir, who said, "Abdullah bin Rabah came to us, and I found that people had gathered around him. He said, 'Abu Qatada narrated to us,'" and he related it. Its isnad is hasan because of Khalid bin Samir, for he is hasan al-hadith.