Then shall I not be ashamed - On the word ashamed, see Job 6:20, note; Psalm 25:2-3, note. The meaning here is, that he would not have occasion to be ashamed; he would not be disappointed; all his hopes would be realized. He would have full evidence of piety; he would enjoy the comforts which he sought in religion; he would feel assured of ultimately obtaining eternal life.
When I have respect unto all thy commandments - literally, "In my looking at all thy commandments." That is, in his regarding them; in his feeling that all were equally binding on him; and in his having the consciousness that he had not intentionally neglected, violated, or disregarded any of them. There can be no true piety except where a man intends to keep all the commands of God. If he makes a selection among them, keeping this one or that one, as may be most convenient for him, or as may be most for his interest, or as may be most popular, it is full proof that he knows nothing of the nature of true religion. A child has no proper respect for a parent if he obeys him only as shall suit his whim or his convenience; and no man can be a pious man who does not purpose, in all honesty, to keep All the commandments of God; to submit to his will in everything.

Then shall I not be ashamed - Every act of transgression in the wicked man tends to harden his heart; and render it callous. If a man who fears God is so unhappy as to fall into sin, his conscience reproaches him, and he is ashamed before God and man. This is a full proof that God's Spirit has not utterly departed from him, and that he may repent, believe and be healed.
Unto all thy commandments - God requires universal obedience, and all things are possible to him whom Christ strengthens; and all things are possible to him that believes. Allow that any of God's commandments may be transgressed, and we shall soon have the whole decalogue set aside.

Then shall I not be ashamed,.... Of hope in God, of a profession of faith in him, and of a conversation agreeable to it before men; nor of appearing before God in his house, worshipping him there; nor at the throne of his grace, nor at the day of judgment, and before Christ at his coming;
when I have respect unto all thy commandments; or "look" (n) at them constantly, as the rule of walk and conversation; and to copy after, as a scholar looks at his copy to write after; and affectionately esteem all his precepts concerning all things to be right, and none of his commandments grievous; and practically, not in the theory only; but observing them in order to practise them, and diligently attending to them, and steadfastly continuing in them; impartially regarding them, one as another; and especially as beholding them fulfilled perfectly in Christ, who is the end of the law for righteousness to everyone that believes.
(n) "quum intuebor", Junius & Tremellius, Piscator, Gejerus, Michaelis.

Respect - A due respect, which implies hearty affection, diligent study, and constant practice. To all - So as not to allow myself in any known sin, or in the neglect of any known duty.