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-reference
Isaiah 38:22
Parallel
Isaiah 38:22 also mentions the same sign of the shadow — Hezekiah's request for a sign.
2 Kings 20:8–21
Parallel
2 Kings 20:8-21 records the same account of Hezekiah's illness and the sign of the shadow, providing a parallel narrative.
2 Kings 20:9
Parallel
2 Kings 20:9 records Isaiah offering Hezekiah the choice of the shadow's direction, the immediate prophetic context of this sign.