Jeremiah 6:27

Here God speaks by way of encouragement to the prophet, and tells him he had made him a fortified tower, that he might both discover the carriages of his people, which is one use of a high tower, Isaiah 21:5,8 Hab 2:1; and also to assure him, though they shall make several attempts against him, yet he shall be kept safe, os in a castle or fortress, Jeremiah 15:20. That thou mayest know and try their way; their courses, actions, and manners, and which way they stand affected; thou mayest bring all to thy strict observation and scrutiny, as goldsmiths or refiners do metals; for so is the word try used, Psalms 66:10, and elsewhere. Hereby he shall be encouraged to reprove them more freely, and with authority, because God doth promise to defend him, that they shall not hurt him; God will give him prudence to see what is amiss, and undauntedness to oppose it.