Brewer's: Nemo Me Impune Lacessit
No one injures me with impunity. The motto of the Order of the Thistle. It was first used on the coins of James VI. of Scotland (James I. of England). A strange motto for Puritans to adopt (Matt. xviii. 21, 22).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894