Isaiah 6:1-13.
This week's haftorah discusses Isaiah's vision of the Heavenly Chariot (the merkavah), a revelation that was experienced by all the Israelites when G-d spoke the Ten Commandments on Mount Sinai -- an event recounted in this week's Torah reading.
Isaiah perceives G-d sitting on a throne surrounded by angels. Isaiah vividly describes the angels and their behavior (in anthropomorphic terms). During the course of this vision, Isaiah volunteers to be G-d's emissary to transmit His message to the Israelites. He is immediately given a depressing prophecy regarding the exile the nation will suffer as punishment for their many sins -- and the Land of Israel will be left empty and desolate.