I mean what proof would there be? Surely any threat like this would be verbal only and in "Friendly Ground" to Jeffries.
Considering this is the guy who was mentored by the woman who took AOC into a private room after she voted "No" on Iron Dome funding one time then after a few minutes AOC left apparently crying and changed her vote to "Present" I'm not inclined to be charitable at ALL to Jeffries.
Literally any negative thing said about him by one of these incoming members as far as I'm concerned is True until proven otherwise with some pretty Ironclad evidence.