It is narrated about Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) that on the day of Yarmuk he lost a cap of his, so he said: Look for it. But it was not found. Then he said: Look for it. So they found it, and it was a worn-out cap. Khalid (may Allah be pleased with him) said: "The Messenger of Allah (peace and blessings be upon him) performed Umrah and shaved his head, and the people rushed for the sides of his hair. I got ahead of them to the hair of his forelock and placed it in this cap. So I have never taken part in any battle while it was with me except that I was granted victory."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3789