Cosmas Indicopleustes

This is Isaac the co-heir of the promises and the blessings of God given to Abraham his father—who was a type of the sacrifice of the Lord Christ, since for three days he travelled on to death, and afterwards returned alive—who on his own shoulders carried the wood for his own sacrifice, as also the Lord Christ carried his own cross on his shoulder—who died in intention and was given his life by God; he in exchange for whom a ram was slain, and whose father heard these words from God: Because thou hast not spared the son whom thou …

The Christian Topography, Book 5 ↗