A page from his manuscript
He is considered the founder of the Hanbali school of fiqh (Islamic jurisprudence).
God created the white race (dhurriyyah bayda) from the right shoulder of Adam and created the black race (dhurriyyah sawda) from Adam's left shoulder. Those of Adam's right shoulder would enter Paradise and those of the left, Perdition.
Ahmad Ibn Hanbal (d855) Ahkam 'ahl Almulul (Rulings about Apostasy)
Taken from: http://www.madinahnet.com/books53/أحكام-أهل-الملل-والردة-من-الجامع-لمسائل-الإمام-أحمد-بن-حنبل-صفحة242
Ahmad ibn Muhammad ibn Hazim told us that Ishaq ibn Mansur told them that he said to Abu Abd Allah: Al-Thawriu (2) was asked about the Raqiq (wild) of the al-Ajam (pagans) brought by sea or other ways. Are they sold if they are Jews and Christians? He said: If they are great, Islam is offered to them, if they accept that, and if they are not from the Jews and the Christians if they have a Muslim to sell them, then they are called to Islam.
In their religion, the Muslim, if he wants to sell them from the people of their religion but do not sell them from the prisoners of war.
Ahmed said: Do not sell young or old Jews and Christians.
I said to Ahmad: Al-Thawriu said: If they are of a religion other than India, or al Zunuy, the Muslim does not sell them from any of the people of Dhimah (1) or from the prisoners of war; because they answer if they are called and they have no religion to adhere to. That their religion does not support them.
Ahmed said: These are not sold, nor those of the people of the Book.
(1) Dhimah: dhimma; the people of the book; the Jews and Christians. The people of the covenant or Mu'ahid is a historical term for non-Muslims living in an Islamic state with legal protection.
(2) maybe Sufyan al-Thawri (716–778 CE), was a Sunni Muslim scholar, jurist, ascetic, traditionist, and founder of the Thawri school of Islamic jurisprudence.