John attested that he himself has heard and seen all these things. He was told to tell others what has been revealed to him because its fulfillment was near, and everyone should be ready.

Revelation 22:8-11

8 I, John, am the one who heard and saw in a vision these things that I have written down. When I had heard and seen them, I immediately knelt down at the feet of the angel who was showing them to me, in order to worship him. 9 But he said to me, “Do not worship me I am just your fellow servant! I am also the fellow servant of your fellow believers who are ◄the prophets/the ones who tell messages that come directly from God►, and I am a fellow servant of those who obey what has been commanded in this book. Instead, worship God!” 10 He also said to me, “Do not keep secret the message about what God has foretold in this book, because it is almost time [MTY] for him to what he has promised to do in this message. 11 Since that time is near, if those who act in an evil manner want to continue to act that way [IRO], that is up to them. God will soon ◄pay them back/punish them► for that. If those who are vile want to continue to be vile [IRO], that is up to them. God will soon ◄pay them back/punish them► for that. Those who are acting righteously should continue to act righteously. And those who are holy should continue to be holy.”