Princes also did sit and speak against me - This would have been applicable to David many times in his life, but it was also applicable to many others, and there is nothing in the language which would limit it to David. It is evident that the author of the psalm had been subject to reproach from those who were of exalted rank; it is clear also that he felt this keenly. It is natural, whether proper or not, that we should feel the reproach and contempt of those in elevated life - the rich, the honored, the learned - more than of those in humbler life. Their good opinion can be of value only as they may be better qualified than others to judge of what constitutes true excellence, or as they may have it in their power to do us more harm, or to do more to aid us in doing good, than others have; but truth and principle are never to be sacrificed that we may secure their favor; and if, in the faithful discharge of our duty, and the zealous adherence to the principles of our religion, we incur their frowns, we are to bear it - as the great Lord and Saviour of his people did. Hebrews 13:13.
But thy servant did meditate in thy statutes - I was engaged in this; I continued to do it; I was not deterred from it by their opposition; I found comfort in it, when they sat and talked against me. This would seem to have reference to some occasion when they were together - in public business, or in the social circle. They, the princes and nobles engaged in the ordinary topics of conversation, or in conversation connected with revelry, frivolity, or sin. Unwilling to participate in this - having different tastes - feeling that it was improper to be one of their companions in such a mode of spending time, or in such subjects of conversation, "he" withdrew, he turned his thoughts on the law of God, he sought comfort in meditation on that law and on God. He became, therefore, the subject of remark - perhaps of their jests - "because" he thus refused to mingle with them, or because he put on what seemed to be hypocritical seriousness, and was (what they deemed) stern, sour, unsocial, as if he thus publicly, though tacitly, meant to rebuke them. Nothing will be more "likely" to subject one to taunting remarks, to rebuke, to contempt, than to manifest a religious spirit, and to introduce religion in any way in the circles of the worldly and the frivolous.

Princes also did sit - It is very likely that the nobles of Babylon did often, by wicked misrepresentations, render the minds of the kings of the empire evil affected towards the Jews.

(d) Princes also did sit [and] speak against me: [but] thy servant did meditate in thy statutes.
(d) When the powers of the world gave false sentence against me, your word was a guide and counsellor to teach me what to do, and to comfort me.

Princes also did sit and speak against me,.... The princes in the court of Saul, who suggested to him that David sought his hurt; the princes of his own court, Absalom, his own son, a prince of the blood, and Ahithophel, a counsellor of state: or the princes of the Gentiles, as Jarchi; so the princes of the Philistines spake against him in a very disdainful manner, "make this fellow return to his place again", 1-Samuel 29:4. Such as these might speak against him, as they sat and rode in their chariots; when at their tables, conversing together; or at their council boards, forming schemes against him: the phrase denotes their constant practice, as Kimchi observes; see Psalm 50:20; herein David was a type of Christ, whom the princes of this world conspired against, and whose life they took away, Psalm 2:2;
but thy servant did meditate in thy statutes; what the princes did or said against him did not divert his mind, or take off his thoughts from the word of God, and the ordinances of it; he thought of them, he spoke and discoursed of them; he declared them, as the word (w) sometimes signifies, and so the Targum takes it here; he was not afraid nor ashamed to profess his regard unto them: as Daniel, when he knew that the presidents and princes had obtained a royal decree, and the writing was signed; yet went into his chamber, as at other times, and kneeled down and prayed to God, Daniel 6:10.
(w) "disserit", Tigurine version, Vatablus, Musculus; "loquitur", Piscator, Gejerus.