Sepher Ha-Razim, a late third/early fourth-century Jewish text, identifies God with the Ancient of Days.
Sepher Ha-Razim: The Book of Mysteries, trans. Michael A. Morgan (Texts and Translations 25; Pseudepigrapha Series 11; Chico, California: Scholars Press, 1983), 84
For ages and ages,
And for an eternity of eternites.
For there is no God apart from Him,
And there is no God beside Him.
Blessed is His name in each generation
And blessed in the heavens on high.
Blessed is HIs name with its might,
And blessed its mention with the beauty of His power.
For as His name so is His praise as it has been said (in
scripture): As if your name, O God as is your praise to
the ends of the earth; your right hand is full of
righteousness.
He brings the pure to reverence Him,
And in His wrath drives away the impure
He moves fountains by His might and strength,
They did not know when He overturned them in His wrath.
He holds the world as a cluster of grapes,
Bearing all that was, is, and will be.
He is the Ancient of Days.