A Revelation
God answered his servant through a vision which was a revelation given to him. He instructed him to write down the vision on tablets so that it could be read. The tablets would have been like the ones that Moses made on which God wrote his Ten Commandments to instruct the Israelites about what he required of them. God wanted his message to be taken to all his people through a herald.
2 And the LORD answered me: “Write the vision; make it plain on tablets, so he may run who reads it.