'Confirming' in the Bible

"Ask for a confirming sign from the Lord your God. You can even ask for something miraculous."

For this reason the sovereign master himself will give you a confirming sign. Look, this young woman is about to conceive and will give birth to a son. You, young woman, will name him Immanuel.

Isaiah replied, "This is your sign from the Lord confirming that the Lord will do what he has said:

Hezekiah said, "What is the confirming sign that I will go up to the Lord's temple?"