Psalms 71:18 - Clarke's commentary and critical notes on the Bible

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. Old and grey-headed - In the ninth verse he mentioned the circumstance of old age; here he repeats it, with the addition of hoary-headedness, which, humanly speaking, was calculated to make a deeper impression in his favor. Though all these things are well known to God, and he needs not our information, yet he is pleased to say, "Come now, and let us reason together." And when his children plead and reason with him, they are acting precisely as he has commanded.