God told Jeremiah to buy a field. It was a perfectly legitimate, normal, everday, around the world, and across the centuries, transaction. Except, it wasn't...
It's a message from God to the prophet Jeremiah telling God's people to bloom where we are planted (wherever that may be), and to help others bloom too!
Isaiah speaks the words of YHWH, telling God's people it's time to stop with the meaningless gestures, and start with the doing the work of Christ in the world.