Against Monotheletism & Monophysitism, these quotations:
“He being one Son, dual in Nature, not dual in Person. Wherefore, do we confess, preaching the truth that Christ our God is perfect God and perfect Man.” — (Troparion of the Resurrection on the Feast of the Holy Forefathers).
O faithful, let us acclaim the lover of the Trinity, great Maximos who taught the God-inspired Faith, that Christ is to be glorified in two natures, wills and energies: and let us cry to him: Rejoice, O herald of the Faith. – Kontakion to St. Maximus the Confessor
We must, then, maintain that Christ has two energies in virtue of His double nature. For things that have diverse natures, have also different energies, and things that have diverse energies, have also different natures. – St. John Damascene