Isaiah 38:7
"And this shall be a sign unto thee from the LORD, that the LORD will do this thing that he hath spoken;"
Cross References (ranked by relevance)
Isaiah 37:30
And this shall be a sign unto thee, Ye shall eat this year such as groweth of itself; and the second year that which springeth of the same: and in the third year sow ye, and reap, and plant vineyards, and eat the fruit thereof.
Genesis 9:13
I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth.
Isaiah 38:22
Hezekiah also had said, What is the sign that I shall go up to the house of the LORD?