Is it farther or further?
1560s, "triumph over in an arrogant way," from Middle French insulter (14c.) and directly from Latin insultare "to assail, to leap upon" (already used by Cicero in sense of "insult, scoff at, revile"), frequentative of insilire "leap at or upon," from in- "on, at" (see in- (2)) + salire "to leap" (see salient (adj.)). Sense of "to verbally abuse, affront, assail with disrespect" is from 1610s. Related: Insulted; insulting.
c.1600 in the sense of "attack;" 1670s as "an act of insulting," from Middle French insult (14c.) or directly from Late Latin insultus, from insilire (see insult (v.)). To add insult to injury translates Latin injuriae contumeliam addere.
insult in·sult (ĭn'sŭlt')
A bodily injury, irritation, or trauma.