John saw a mighty angel coming down out of heaven and holding a small open scroll. When the angel shouted, it thundered several times, but a voice from heaven prohibited John from recording what the thunder said. The angel affirmed that the living Creator of the universe would no longer delay in completing what he planned for his creation.

Revelation 10:1-7

10 In the vision I saw another mighty angel that was coming down out of heaven. A cloud surrounded him. There was a rainbow over his head. His face shone [SIM] like the sun. His legs looked like pillars of fire. 2 He had in his hand a small scroll that was open. He set his right foot on the ocean and his left foot on the land. 3 He shouted something with a loud voice, a voice like the roar of a lion. When he shouted this, it thundered seven times, speaking words that I could understand. 4 When it thundered like that, I was about to write the words that I heard, but a voice from heaven said to me, “Keep secret what the thunder said! Do not write it down!” 5 Then the angel whom I had seen standing on the ocean and the land raised his right hand toward heaven, 6 and he asked the one who lives forever, the one who created heaven and everything that is in it, who created the earth and everything that is in it, and who created the ocean and everything that is in it, to affirm that what he said was true. He said that he would surely no longer delay what he had planned to do. 7 He said that when the time came for the seventh angel to blow his trumpet, he would complete what God had secretly planned, just like he announced long ago to his servants, the prophets.