The Ecthesis (from Greek εκθσις, "statement of faith") was a formula issued in 638 by Emperor Heraclius.
It forbid the mention of "energies," either one or two, in the person of Jesus Christ. It also asserted that the two natures of Christ were united in a single will (e.g., Monothelitism). It had been drafted earlier in 638 by Patriarch Sergius of Constantinople after consultation with Pope Honorius of Rome. It was accepted by synods held in the Imperial capital, but quickly repudiated by Heraclius as well as Honorius' two successors (Popes Severinus and John IV).
The text of the Ecthesis is preserved in the Acta of the Lateran Council of 649.
The Oxford Dictionary of the Christian Church (3rd ed.), p. 528