Musnad Ahmad 25:67

Sufyan narrated to us, from Ibn Jud'an, from 'Amr ibn Harmalah, from Ibn 'Abbas: The Prophet, peace and blessings of Allah be upon him, drank, and Ibn 'Abbas was on his right, and Khalid ibn al-Walid was on his left. The Prophet, peace and blessings of Allah be upon him, said to him: "The drink is yours, but if you wish, you may prefer Khalid with it." He said: "I will not prefer anyone over the remainder of the drink of the Messenger of Allah, peace and blessings of Allah be upon him."