Sayyiduna Iyad bin Himar (may Allah be pleased with him) (who had not yet become Muslim at that time) came to the Messenger of Allah (peace and blessings be upon him) with a she-camel and a riding mount and presented it as a gift. The Messenger of Allah (peace and blessings be upon him) said: "Lead it along." So he led it along. The Prophet of Allah (peace and blessings be upon him) called out to him: "O Iyad bin Himar, have you become Muslim?" He said: No. He (peace and blessings be upon him) said: "Then keep your she-camel with you, for Allah has forbidden us the gifts of the polytheists."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15068