Cosmas Indicopleustes

For the very Prophet through whom the retrogression of the sun was effected, when, by means of the dread sign, he had in reality confuted the theory of the Babylonians, by showing that the heaven is not a revolving sphere, and that they held an opinion that is erroneous, this very Prophet not long afterwards speaks thus of the figure of the heaven: He that established the heaven as a vaulted chamber; and again: The Lord God who made the heaven and fixed it, thus declaring at once that it is a vault, and that it is established and …

The Christian Topography, Book 8 ↗

Ambrose of Milan

Therefore, it is enough to mention the qualities and substance of the heavens that we find in the writings of Isaiah, who expressed the nature of the celestial sphere in ordinary and familiar language, saying that God has made the heavens firm like smoke, not wanting to reveal its subtle and immaterial nature. And he also speaks of its appearance, saying that God has made the heavens like a vault, within which all things in the sea and on land are enclosed. …

The Six Days of Creation, Book 1, Chapter 6 ↗

Thomas Aquinas

And as to their creator: it is he that sits upon the globe of the earth, for it is spherical, as though governing it, and the inhabitants thereof are as locusts, in respect to the magnitude of the earth, or of God himself; also from the creation of heavenly creatures: he that stretches out, as to the magnitude of heaven, as nothing, as to the subtlety of its substance, as a tent, for himself, as that in which his power first shines out among corporeal things, as to power; or as in the dwelling of the angels and saints, as to dignity; …

Commentary on Isaiah ↗