Musnad Ahmad 56:1

Rawh narrated to us, Ibn Jurayj narrated to us, and al-Dahhak ibn Makhlad said: Ibn Jurayj informed us, and Abdullah ibn al-Harith said: Ibn Jurayj presented to me, he said: Amr ibn Abi Sufyan informed me that Amr ibn Abi Safwan informed him. Al-Dahhak and Abdullah ibn al-Harith said: That Amr ibn Abdullah ibn Safwan informed him that Kaladah ibn al-Hanbal informed him that Safwan ibn Umayyah sent him during the Conquest [of Mecca] with milk, a young kid, and *thaghabis* (thistle shoots), while the Prophet, peace and blessings of Allah be upon him, was at the upper part of the valley. He said: So I entered upon him without greeting and without asking permission. The Prophet, peace and blessings of Allah be upon him, said: "Go back and say: 'Peace be upon you, may I enter?'" After Safwan had embraced Islam, Amr said: Umayyah ibn Safwan informed me of this report, and he did not say: "I heard it from Kaladah." Al-Dahhak and Ibn al-Harith said: And that was after he had embraced Islam. Al-Dahhak and Abdullah ibn al-Harith said: With milk and a young kid.