Since then these things are related in the Evangelists, they are not surely false, but as when He willed He became Man, so likewise when He willed He took into His human soul these passions for the sake of adding assurance to the dispensation. We indeed have these passions by reason of the weakness of our human nature; not so the Lord Jesus, whose weakness was of power.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: City of God, book xiv, ch. 9