Tradition
St. Cyril of Jerusalem
Catechetical Lectures
Book 6 › Introduction
Concerning the Unity of God. On the Article, I Believe in One God. Also Concerning Heresies.
Isaiah 45:16, 17. (Sept.)
Sanctify yourselves unto Me, O islands. Israel is saved by the Lord with an everlasting salvation; they shall not be ashamed, neither shall they be confounded for ever, etc.
Source: Catechetical Lectures (New Advent)