Isaiah 50:7 - Matthew Poole's English Annotations on the Holy Bible

For; or rather, But, as this particle is oft rendered. For God's favour is here opposed to the injuries of men. The Lord God will help me; though as a man I am weak and inconsiderable, yet God will strengthen me to go through my great and hard work. Therefore shall I not be confounded; therefore I assure myself of success in my employment, and of victory over all mine enemies. Therefore have I set my face like a flint; I have hardened myself with resolution and courage against all opposition. So this or the like phrase is used Ezekiel 3:8,9, which elsewhere signifies obstinacy and impudence, as Jeremiah 5:3 Malachi 7:12; so that it notes any settled and unmovable purpose, whether good or evil.