baited breath

I think the oldest written example of the phrase is in the Merchant of Venice, though I may be wrong.

“Shall I bend low and in a bondman’s key,
With bated breath and whispering humbleness, Say this;
‘Fair sir, you spit on me on Wednesday last;
You spurn’d me such a day; another time
You call’d me dog; and for these courtesies
I’ll lend you thus much moneys’?”

I’m defiling my hand like a motherfucker!

No, motherfucking is something different.