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He loves him as the Devil loves holy water, i.e. hates him mortally. Holy water, according to the Roman Catholics, having the virtue to chase away the Devil and his imps.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Holy Lamb * HollowNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes
Buy a modern reprint of this book from Amazon CA; US;
Francis Grose was independently wealthy, having inherited money from his father, a jeweller. Finding himself overspending, he published a number of books; his Provincial Glossary seems to have been the starting-point for the Vulgar Tongue reproduced here.