Believe you me!

Just wondering if anyone knew the origins of the the expression 'Believe you me...' and how it came by that form which when used today sounds slightly archaic.

Was there once an "in" between 'you' and 'me'?

Cheers.

From Eric Partridge, Dictionary of Catch Phrases: American and British, from the Sixteenth Century to the Present Day:

"'believe you me!' a vaguely emphatic, somewhat conventional catchphrase of C20. Granville notes that 'this is the [naval] Gunnery Instructor's emphasis to any statement. 'Believe you me, that is the only way to do the job.' . . ."

From me: "In" would change the meaning. "Believe you me" doesn't mean "Believe in me," it means "Believe me."