The Bible speaks of old age and gray hairs in Leviticus, Proverbs, and the Psalms.
In Leviticus 19:32:
32 Thou shalt rise up before the hoary head, and honour the face of the old man, and fear thy God: I am the LORD.
In Proverbs 16:31:
31 The hoary head is a crown of glory, if it be found in the way of righteousness.
In Psalms 71:9:
9 Cast me not off in the time of old age; forsake me not when my strength faileth.