Green’s Dictionary of Slang

grumble v.

(US tramp) to pray.

1927

‘Jargon of the Und.’ in DN V 449: Grumble, To pray.

SE in slang uses

In compounds

grumble-guts (n.) (also grumble-gizzard) [Yorks. dial.; note synon. Lancashire dial. grumble-belly]

a habitual complainer.

1798		J. Gillray 24 Oct. [cartoon title] John Bull taking a Luncheon; – or – British Cooks, cramming Old Grumble-Gizzard, with Bonne-Chère.
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc.
1888		S.O. Addy Sheffield Gloss. 98: Grumble-Guts, a discontented person.
1927		E. Wallace Squeaker (1950) 54: Mr Grumbleguts is a bit late this morning.
1969		B. Mason Awatea (1978) 68: No good hangin’ round here with old grumble-guts pokin’ in his oar.

In phrases

grumble in the gizzard (v.)

to be annoyed, but to keep one’s feelings to oneself.

c.1698		B.E. Dict. Canting Crew n.p.: Grumbling of the gizzard, Murmuring, Muttering, Repining, Resenting.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.