And knowest his will - The will or commands of God. This knowledge they obtained from the Scriptures; and of course in this they were distinguished from other nations.
And approvest - The word used here is capable of two interpretations. It may mean either to distinguish, or to approve. The word is properly and usually applied to the process of testing or trying metals by fire. Hence, it comes to be used in a general sense to try or to distinguish anything; to ascertain its nature, quality, etc.; Luke 12:56. This is probably its meaning here, referring rather to the intellectual process of discriminating, than to the moral process of approving. It could not, perhaps, be said with propriety, at least the scope of the passage does not properly suppose this, that the Jew approved or loved the things of God: but the scope of the passage is, that the Jew valued himself on his knowledge of what was conformable to the will of God; see the notes at Romans 14.
The things that are more excellent - The word translated here “more excellent” denotes properly the things that differ from others, and then also the things that excel. It has an ambiguity similar to the word translated “approved.” If the interpretation of that word above given is correct, then this word here means those things that differ from others. The reference is to the rites and customs, to the distinctions of meats and days, etc., prescribed by the Law of Moses. The Jew would pride himself on the fact that he had been taught by the Law to make these distinctions, while all the pagan world had been left in ignorance of them. This was one of the advantages on which he valued himself and his religion.
Being instructed ... - That is, in regard to the one God, his will, and the distinguishing rites of his worship.