Declaration of Belief, circa August 1835 [D&C 134]

the earth, and warn the righteous to save themselves from the  corruption of the world; but we do not believe it right to inter fere with bond-servants, neither preach the gospel to, nor bap tize them, contrary to the will and wish of their masters, nor  to meddle with, or influence them in the least to cause them  to be dissatisfied with their situations in this life, thereby jeop ardizing the lives of men: such interference we believe to be  unlawful and unjust, and dangerous to the peace of every Gov ernment allowing human beings to be held in servitude. [p. 254]
Declaration of Belief, Kirtland, OH, ca. Aug. 1835; in Doctrine and Covenants, 1835 ed., pp. 252–254.