It is human nature to hate the man whom you have to hurt.

[Proprium humani ingenii est odisse quem laeseris.]

Tacitus (c.56-c.120) Roman historian, orator, politician [Publius or Gaius Cornelius Tacitus]

Agricola, ch. 42 (AD 98)
    (Source)

Alt trans: "It belongs to human nature to hate those you have injured."