Revelation 2:23 in the King James Version
And I will kill her children with death; and all the churches shall know that I am he which searcheth the reins and hearts: and I will give unto every one of you according to your works.
Context
22 Behold, I will throw her and those who commit adultery with her into a bed of great oppression, unless they repent of her works.
23 I will kill her children with Death, and all the assemblies will know that I am he who searches the minds and hearts. I will give to each one of you according to your deeds.
24 But to you I say, to the rest who are in Thyatira—as many as don’t have this teaching, who don’t know what some call ‘the deep things of Satan’—to you I say, I am not putting any other burden on you.