Grudge
late Middle English: variant of obsolete grutch ‘complain, murmur, grumble’, from Old French grouchier, of unknown origin. Compare with grouch.
wiktionary
A variant of grutch (mid 15th-century, younger than begrudge), from Middle English grucchen(“to murmur, complain, feel envy, begrudge”), from Old French grouchier, groucier(“to murmur, grumble”) [1], of Germanic origin, akin to Middle High German grogezen(“to howl, wail”), German grocken(“to croak”). Compare also Old Norse krytja(“to murmur”), Old High German grunzen(“to grunt”).
etymonline
grudge (v.)
mid-15c., "to murmur, complain," variant of grutch. Meaning "to begrudge, envy, wish to deprive of" is c. 1500. Related: Grudged; grudges; grudging; grudgingly.
grudge (n.)
"ill will excited by some special cause," late 15c., from grudge (v.).