"Even when I am old and grey, do not forsake me, my God, till I declare your power to the next generation." (Psalm 71:18)
Psalm 71 is the prayer of an old person who has trusted God from youth and continues to trust in age. It is one of the few psalms that explicitly address the experience of growing old in faith. The psalmist has taken refuge in God since birth, has been sustained since the womb. Now enemies say that God has forsaken this aged person, that there is no one to rescue them. The prayer that rises against this accusation is the testimony of a lifetime: you have taught me from my youth, and I have always told of your wonderful deeds.
Even when I am old and grey, do not forsake me, my God, till I declare your power to the next generation, your mighty acts to all who are to come. This is the great purpose of the prayer: not survival for its own sake, but survival in order to testify. The old person who has lived through decades of God's faithfulness has a testimony that no young person can have. The accumulated evidence of a lifetime of divine care is irreplaceable. The prayer for continued life is a prayer for continued testimony.
The psalm is honest about the troubles the long life has included: many troubles, severe and bitter, pressed down to the depths of the earth. But you will restore my life again; from the depths of the earth you will again bring me up. The hope of restoration is grounded in a history of having been restored before. The person who has watched God raise them from the depths more than once has a basis for expecting it again. The accumulated experience of God's faithfulness is the senior believer's greatest asset.
Brothers and sisters, if you are among those who are old and grey, Psalm 71 is your psalm. Your testimony has a power that youth cannot replicate. Declare it to the next generation while you can. And if you are young, seek out the old and grey who have this testimony, and listen. They have something you cannot yet have.
Lord God, you have been my confidence since youth and my hope since birth. Even when I am old and grey, do not forsake me until I have declared your power to the next generation. You have done great things. Let my life declare them. Through Christ our Lord. Amen.