The Lord is known by the judgment which he executeth - By what; he does in his dealings with men, in dispensing rewards and punishments, bestowing blessings upon the righteous, and sending punishments upon the ungodly. That is, his character can be learned from his dealings with mankind; or, by studying the dispensation of his Providence, we may learn what he is. This is always a fair and proper way of estimating character, alike in regard to God and man; and it is proper, at all times, to study what God does, to learn what he is.
The wicked is snared in the work of his own hands - The same sentiment which is expressed here occurs in Psalms 7:16. The idea is that the wicked are the cause of their own destruction; their own devices and designs are the means of their ruin, and they are made their own executioners. It is this to which the writer seems particularly to refer in the former part of the verse, when he says that “the Lord is known by the judgment which he executeth.” This great principle is brought out in his dealings with human beings, that the course which wicked men pursue is the cause of their own ruin. The laws of God in a great measure execute themselves, and men bring upon themselves their own destruction. It is the highest perfection of government to make ttle laws execute themselves.
Higgaion - Margin, “Meditation.” This word occurs elsewhere only in the following places, Psalms 19:14, rendered meditation; Psalms 92:3, rendered solemn sound; Lamentations 3:62. rendered device. Its proper meaning is, murmur; muttering; the utterance of a low sound, as the low sound of a harp; or the murmuring or muttering of one who talks to himself; and then meditation. Compare the notes at Psalms 2:1, on the word “imagine,” Margin, meditate, - the verb from which this is derived. Gesenius supposes that it is here a musical sound. So it is understood by the Septuagint - ᾠδὴ διαψάλματος ōdē diapsalmatos. It is not known why it is introduced here. There seems to be nothing in the sense which demands it, as there is no particular reason why the reader should pause and meditate here rather than in any other place in the psalm. It is doubtless a mere musical pause, though perhaps indicating the kind of pause in the music, as some special sound or interlude on the musical instrument that was employed.
Selah - Another musical term, see the notes at Psalms 3:2. This indicates a general pause; the word Higgaion denotes the particular kind of pause.