Constitutional FAQ Answer #34
Q34. "I have been challenged to find the text of a thirteenth amendment which was proposed but not ratified. I believe it derives from the Crittenden Compromise and came about in 1860-1861."
A. In 1861, an amendment was sent to the states for ratification. It prohibited the Federal government from interfering in the internal policies of the states, with slavery being mentioned specifically. If ratified at the time of its submission, it would have been the 13th Amendment. The amendment never was ratified, and is, in fact, still outstanding. You can find information about it and other failed amendments on my Amendments Page.
The text of the amendment:
No amendment shall be made to the Constitution which will authorize or give to Congress the power to abolish or interfere, within any State, with the domestic institutions thereof, including that of persons held to labor or service by the laws of said State.
This was passed in the 36th Congress. If you can get your hands on the Congressional Record from that Congress, you can likely find out a lot more info.