The Lord preserveth the simple - The Septuagint renders this “babes” - νήπια nēpia. The Hebrew word has reference to simplicity or folly, as in Proverbs 1:22. It then refers to those who are the opposite of cautious or cunning; to those who are open to persuasion; to those who are easily enticed or seduced. The verb from which the word is derived - פתה pâthâh - means to open, to expand; then, to be open, frank, ingenuous, easily persuaded or enticed. Thus it may express either the idea of being simple in the sense of being foolish, easily seduced and led astray; or, simple in the sense of being open, frank, ingenuous, trustful, sincere. The latter is evidently its meaning here. It refers to one of the characteristics of true piety - that of unsuspecting trust in God. It would describe one who yields readily to truth and duty; one who has singleness of aim in the desire to honor God; one who is without guile, trick, or cunning. Such a man was Nathanael John 1:47 : “Behold an Israelite indeed, in whom is no guile.” The Hebrew word used here is rendered simple, Psalms 19:7; Psalms 119:130; Proverbs 1:4, Proverbs 1:22, Proverbs 1:32; Proverbs 7:7; Proverbs 8:5; Proverbs 9:4; Proverbs 14:15, Proverbs 14:18; Proverbs 19:25; Proverbs 21:11; Proverbs 22:3; Proverbs 27:12; Ezekiel 45:20; and foolish, Proverbs 9:6. It does not elsewhere occur. The meaning here is, that the Lord preserves or keeps those who have simple and unwavering trust in him; those who are sincere in their professions; those who rely on his word.
I was brought low - By affliction and trial. The Hebrew literally means to hang down, to be pendulous, to swing, to wave - as a bucket in a well, or as the slender branches of the palm, the willow, etc. Then it means to be slack, feeble, weak, as in sickness, etc. See the notes at Psalms 79:8. Here it probably refers to the prostration of strength by disease.
And he helped me - He gave me strength; he restored me.