This will be a sign to you from the LORD that He will do what He has promised:

Judges 6:17
Gideon answered, "If I have found favor in Your sight, give me a sign that it is You speaking with me.

Judges 6:21
Then the angel of the LORD extended the tip of the staff that was in his hand and touched the meat and the unleavened bread. And fire flared from the rock and consumed the meat and the unleavened bread. Then the angel of the LORD vanished from his sight.

1 Kings 13:3
That day the man of God gave a sign, saying, "The LORD has spoken this sign: 'Surely the altar will be split apart, and the ashes upon it will be poured out.'"

2 Kings 20:9
And Isaiah had replied, "This will be a sign to you from the LORD that He will do what He has promised: Would you like the shadow to go forward ten steps, or back ten steps?"

2 Chronicles 32:31
And so when ambassadors of the rulers of Babylon were sent to him to inquire about the wonder that had happened in the land, God left him alone to test him, that He might know all that was in Hezekiah's heart.

Isaiah 7:11
"Ask for a sign from the LORD your God, whether from the depths of Sheol or the heights of heaven."

Isaiah 7:14
Therefore the Lord Himself will give you a sign: Behold, the virgin will be with child and will give birth to a son, and will call Him Immanuel.

Isaiah 37:30
And this will be a sign to you, O Hezekiah: This year you will eat what grows on its own, and in the second year what springs from the same. But in the third year you will sow and reap; you will plant vineyards and eat their fruit.

Isaiah 38:22
And Hezekiah had asked, "What will be the sign that I will go up to the house of the LORD?"

And this shall be a sign to you from the LORD, that the LORD will do this thing that he has spoken;