Job 42:16 shows the fulfillment of this promise — Job lives long and sees descendants, returning to youthful vigor.

Joshua 14:11 directly states Caleb's strength is as in his youth — a precise parallel to 'return to the days of his youth'.

In 2 Kings 5:14, Naaman's flesh is restored like a child's — the exact same image of physical renewal promised here.

Psalm 103:5 says your youth is renewed like the eagle's — the same theme of restored vitality as here.

Deuteronomy 34:7 describes Moses' undimmed eye and unabated vigor — a similar picture of sustained youthfulness in old age.

Joshua 14:10 has Caleb, at 85, still alive and strong — echoing the promise of renewed youth and longevity.