Green’s Dictionary of Slang

enough! stop!

1853		W.D. Arnold Oakfield (1854) 42: ‘And if you pass,’ say my dear good-natured friends, ‘you may get an appointment.’ ‘Bus!’ (you see my Hindostanee knowledge already carries me the length of that emphatic monosyllable).
1886		Yule & Burnell Hobson-Jobson (1996) 133/1: BUS, adv. P.-H. bas, ‘enough.’ Used commonly as a kind of interjection : ‘Enough ! Stop !’ [...] Few Hindustani words stick closer by the returned Anglo-Indian.