2 Samuel 21:15

And now, behold, the Lord hath kept me alive, as he said, these forty and five years, even since the Lord spake this word unto Moses, while the children of Israel wandered in the wilderness: and now, lo, I am this day fourscore and five years old. As yet I am as strong this day as I was in the day that Moses sent me: as my strength was then, even so is my strength now, for war, both to go out, and to come in.

And it came to pass after this, that there arose war at Gezer with the Philistines; at which time Sibbechai the Hushathite slew Sippai, that was of the children of the giant: and they were subdued.

But when the Philistines heard that they had anointed David king over Israel, all the Philistines came up to seek David; and David heard of it, and went down to the hold.

And the Philistines came up yet again, and spread themselves in the valley of Rephaim.

And David did so, as the Lord had commanded him; and smote the Philistines from Geba until thou come to Gazer.

In the day when the keepers of the house shall tremble, and the strong men shall bow themselves, and the grinders cease because they are few, and those that look out of the windows be darkened,

Cast me not off in the time of old age; forsake me not when my strength faileth.

For all flesh is as grass, and all the glory of man as the flower of grass. The grass withereth, and the flower thereof falleth away: But the word of the Lord endureth for ever. And this is the word which by the gospel is preached unto you.

Hast thou not known? hast thou not heard, that the everlasting God, the Lord, the Creator of the ends of the earth, fainteth not, neither is weary? there is no searching of his understanding. He giveth power to the faint; and to them that have no might he increaseth strength. Even the youths shall faint and be weary, and the young men shall utterly fall:

Thus saith the Lord, Let not the wise man glory in his wisdom, neither let the mighty man glory in his might, let not the rich man glory in his riches: But let him that glorieth glory in this, that he understandeth and knoweth me, that I am the Lord which exercise lovingkindness, judgment, and righteousness, in the earth: for in these things I delight, saith the Lord.

Now also when I am old and grayheaded, O God, forsake me not; until I have shewed thy strength unto this generation, and thy power to every one that is to come.

My flesh and my heart faileth: but God is the strength of my heart, and my portion for ever.