Textual Crisis

Ok. I’m having a crisis of Biblical textual criticism.

I remember being taught as a child the phrase “Jesus set his face like flint to go to Jerusalem.” I’m reading today in Isaiah 50:7 where it says, “For the Lord GOD will help Me; Therefore I will not be disgraced; Therefore I have set My face like a flint, And I know that I will not be ashamed.” And I thought, “oh, cool, it’s a quote,” and went to make a note of what the New Testament reference was.

Only I can’t find it. All I can find is Luke 9:51, which reads in every translation I can find, something like “He steadfastly set his face to go to Jerusalem.” I can’t even find the word “flint” in the new testament. So, where am I getting the phrase, “Set his face like flint to go to Jerusalem?” I know I didn’t make that up. Somebody taught it to me.