In “Sukhodol” (1911), Ivan Bunin documents a saying “a wolf is no affine to a horse” (volk koniu ne svojstvennik) (Bunin I. A. Derevnia. Moscow, 1981, p. 171).
I personally have never heard this expression but recall a similar one “A horseman is no partner to a person on foot” (konnyj peshemu ne tovarisch). It’s likely that “affine” is an early symbol of contractual obligations superseded during the Soviet times by a new label generalized social contract – tovarisch “partner, comrade.”