It is narrated from Sayyiduna Mas'ud bin al-Dahhak al-Lakhmi (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) named him Muta' and said: "O Muta'! You are one who is obeyed (muta') among your people." And he said: "Go to your companions." And he mounted him on a piebald horse, gave him the banner, and said: "Whoever comes under this banner of mine is safe from punishment."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17916