Theodoret of Cyrus: Impassibility of God

He also indicated creation's change for the better that was due to him, and his own lack of beginning or extinction; you are the same and your years will not fail, he says, note, meaning, You were not made, but you are, and you admit of no change, being always the same. This suggests also the impassibility of the divinity; if it suffered, how is it the same? After all, it would be changed, and if it passed three days in death, its years would fail. Both the prophet and the apostle, however, the one writing the testimony and the other using it, emphasize that he is always the same, and his years will not fail.

- Theodoret of Cyrus (around A.D. 393 to around A.D. 457), Commentary on Hebrews, Chapter 1, in Theodoret of Cyrus, Commentary on the Letters of St. Paul, Volume 2, p. 144 (2001), Robert C. Hill translator.