From Longman Dictionary of Contemporary Englishbelieve (you) mebelieve (you) meTRUEused to emphasize that something is definitely true There’ll be trouble when they find out about this, believe you me! → believe
Examples from the Corpus
believe (you) me• No, it's too far to walk, believe me.• But I could see from the look in his eyes that he did not believe me.• Oh, please, you must believe me.• You think they gon na believe me?• There is nothing to do now but wait, and believe me, midnight seems like a week away.• And believe me, my wife does not enjoy reminding me twice.• Conrad and Philippa don't believe me, not really.• Those who did believe me offered no solace; only sympathy and empty platitudes.• No, no, believe me, the less she knows of my activities, the better. 