Jesus issued this warning when he sent his angel with letters to the early seven churches in the revelation of John (Revelation 1:11).
“He that hath an ear, let him hear what the Spirit saith unto the churches; he that overcometh shall not be hurt of the second death” (Revelation 2:11).
“As many as I love, I rebuke and chasten: be zealous therefore, and repent. Behold, I stand at the door, and knock: if any man hear my voice, and open the door, I will come in to him, and will sup with him, and he with me. To him that overcometh will I grant to sit with me in my throne, even as I also overcame, and am set down with my Father in his throne. He that hath an ear, let him hear what the Spirit saith unto the churches” (Revelation 3:19-22).
“And, behold, I come quickly; and my reward is with me, to give every man according as his work shall be” (Revelation 22:12).