This question concerns whether or not a Greek phrase used in the NT is a Hebrew idiomatic usage. If this is off topic, please let me know and I'll delete the question.
The phrase is:
Philippians 3:5 I was circumcised on the eighth day, from the people of Israel and the tribe of Benjamin, a Hebrew of Hebrews. I lived according to the law as a Pharisee.
William,
There is no 'Hebrew of Hebrews' or 'Israelite of Israelites' in the OT.
In the OT, we do have the expressions: holy of holies, king of kings, Lord of Lords, God of Gods, heaven of heavens - and maybe others.
These expressions refer to the ultimate of that group.
All of these are in the NT except for God of Gods and heaven of heavens.