Here we have David's testimony from his own experience, 1. Of the vanity of the world and its insufficiency to make us happy: I have seen an end of all perfection. Poor perfection which one sees an end of! Yet such are all those things in this world which pass for perfections. David, in his time, had seen Goliath, the strongest, overcome, Asahel, the swiftest, overtaken, Ahithophel, the wisest, befooled, Absalom, the fairest, deformed; and, in short, he had seen an end of perfection, of all perfection. He saw it by faith; he saw it by observation; he saw an end of the perfection of the creature both in respect of sufficiency (it was scanty and defective; there is that to be done for us which the creature cannot do) and in respect of continuance; it will not last our time, for it will not last to eternity as we must. The glory of man is but as the flower of the grass. 2. Of the fulness of the word of God, and its sufficiency for our satisfaction: But thy commandment is broad, exceedingly broad. The word of God reaches to all cases, to all times. The divine law lays a restraint upon the whole man, is designed to sanctify us wholly. There is a great deal required and forbidden in every commandment. The divine promise (for that also is commanded) extends itself to all our burdens, wants, and grievances, and has that in it which will make a portion and happiness for us when we have seen an end of all perfection.

I understand more than the ancients,.... Than those that had lived in ages before him; having clearer light given him, and larger discoveries made unto him, concerning the Messiah, his person and offices particularly, as it was usual for the Lord to do; or than aged men in his own time: for though wisdom, knowledge, and understanding, may be reasonably supposed to be with ancient men; who have had a long experience of things, and have had time and opportunity of making their observations, and of laying up a stock of knowledge; and this may be expected from them, and they may be applied to for it; yet this is not always the case; a younger man, as David was, may be endued with more knowledge and understanding than such; so Elihu; see Job 8:8, Job 32:6. Or, "I have got understanding by the ancients"; so Kimchi; though the other sense seems preferable;

because I keep thy precepts; keep close to the word; attend to the reading of it, and meditation on it; keep it in mind and memory, and observe to do the commands of it; and by that means obtained a good understanding, even a better one than the ancients; especially than they that were without it, or did not carefully attend unto it; see Psa 111:10.