Pope Dionysius

3rd century · AD 268 · Early Fathers (before Nicaea) · 2 passages

In his own words on John

John 10:30
Neither then may we divide into three Godheads the wonderful and divine Monad; nor disparage with the name of "work" the dignity and exceeding majesty of the Lord; but we must believe in God the Father Almighty, and in Christ Jesus His Son, and in the Holy Ghost, and hold that to the God of the universe the Word is united. For "I," says He, "and the Father are one;" and, "I in the Father and the Father in Me." For thus both the Divine Triad, and the holy preaching of the Monarchy, will be preserved.
Against those who divide and cut to pieces the Divine Monarchy (as quoted in Athanasius, De Decretis, Chapter 26)
John 14:10
Neither then may we divide into three Godheads the wonderful and divine Monad; nor disparage with the name of "work" the dignity and exceeding majesty of the Lord; but we must believe in God the Father Almighty, and in Christ Jesus His Son, and in the Holy Ghost, and hold that to the God of the universe the Word is united. For "I," says He, "and the Father are one;" and, "I in the Father and the Father in Me." For thus both the Divine Triad, and the holy preaching of the Monarchy, will be preserved.
Against those who divide and cut to pieces the Divine Monarchy (as quoted in Athanasius, De Decretis, Chapter 26)

Quoted verbatim from public-domain English translations of the fathers — Aquinas's Catena Aurea, the Ante-Nicene and Nicene & Post-Nicene Fathers, and related editions. Each quotation links to its source.