Verse 20. - This gate of the Lord, into which the righteous shall enter; rather, this is the gate of the Lord: the righteous [and they alone] shall enter by it. "This verse seems to stand apart - a solo, chanted by a voice out of the temple gate" (Kay). Though sinners doubtless sometimes entered (2 Kings 11:13; 2 Chronicles 26:16-20; John 2:14), none but the righteous had any right to enter.
This gate of the Lord, into which the righteous shall enter. This seems to be spoken by some other person or persons, distinct from David and the Messiah, pointing at some particular and principal gate, upon hearing the above word: by which is meant, not the gate of the house of the sanctuary of the Lord, as the Targum; but the Messiah himself, afterwards spoken of as the stone rejected by the builders, and made the head of the corner; who is the way of access to God; the door into the church or sheepfold; the strait gate that leads to eternal life; by which none but righteous persons enter into heaven; even such who are made righteous, through the imputation of his righteousness to them; see John 10:1.