Lenin Warned Against Stalin

This did not mean that Stalin would automatically become Lenin’s successor. Indeed, his ambitions incurred Lenin’s distrust to the extent that, in his Political Testament, Lenin warned against Stalin and, in a codicil added in January 1923, recommended his removal from the post of General Secretary. However, Lenin died before any further action could be taken and Stalin was soon able to put himself forward as one of the contenders for the succession.

--Stephen J. Lee, Stalin and the Soviet Union, Questions and Analysis in History (London: Taylor and Francis e-Library, 2005), 1.