How then should men suppose Him who is really the Son to be made or created, when God the Father thundered from above, This is my beloved Son! as if He said, Not one of My sons, but He who is truly and by nature My Son, according to whose example the others are adopted, He ordered them then to obey Him, when He added, Hear ye him. And to obey Him more than Moses and Elias, for Christ is the end of the Law and the Prophets. Hence the Evangelist adds significantly, And when the voice was past, Jesus was found alone.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: in Thes. lib. 12. c. 14.