The interpretation timeline
Psalm 127:4 Douay-Rheims

Behold, thus shall the man be blessed that feareth the Lord.

A.D. 430 – 1875 3 witnesses

Patristic

before A.D. 750
430
A.D.
Augustine of Hippo Patristic
A.D. 354–430
“...Such children ought therefore to be "around" the Lord's "table, like olive-branches." A complete Vine it is, a great bliss: who would now refuse to be there? When thou seest any blasphemer have a wife, children, grandchildren, and thyself perchance without them, envy them not; discern that the promise hath been fulfilled in thee also, but spiritually. If therefore we have, why have we? Because we fear the Lord. "Lo, thus shall the man be blessed that feareth the Lord" [Psalm 128:4]. He is the man, who is also the men; and the men are one man; because many are one, because Christ is One.”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Behold, that thus shall the man be blessed that feareth the Lord. In the manner before described, and in the instances already given, as well as in the following; this is said to raise attention, and fix a sense of the blessedness of such persons; and who are further addressed, and pronounced happy, in the next verses. Behold, that thus shall the man be blessed that feareth the Lord. In the manner before described, and in the instances already given, as well as in the following; this is said to raise attention, and fix a sense of the blessedness of such persons; and who are further addressed, and pronounced happy, in the next verses. Psalms 128:5 psa 128:5 psa 128:5 psa 128:5The Lord shall bless thee out of Zion,.... The church of God, where he dwells, out of which he shines, even the Word of the Lord, as the Targum in the king's Bible; and where he commands his blessings of grace to descend on his people, even life for evermore, Psa 133:3. Here he blesses them with his word and ordinances, which are the goodness and fatness of his house, and with his presence in them; so that the man that fears God is blessed, not only in his person, and in his family, but in the house of God; see Psa 118:26; and thou shall see the good of Jerusalem all the days of thy life; the goodness of God in Jerusalem, which is another name for the church of God; the beauty of the Lord in his house and ordinances; his power and his glory in the sanctuary: or should see the church of God in prosperous circumstances all his days; true religion flourish, the power of godliness in the professors of it; the word and ordinances blessed to the edification of saints, and many sinners converted and gathered in. This may be applied to Christ, Isa 53:11.”
Source
1875
A.D.
Keil & Delitzsch Lutheran
1861–1875
“Pointing back to this charming picture of family life, the poet goes on to say: behold, for thus = behold, thus is the man actually blessed who fears Jahve. כּי confirms the reality of the matter of fact to which the הנּה points. The promissory future in Psa 128:5 is followed by imperatives which call upon the God-fearing man at once to do that which, in accordance with the promises, stands before him as certain. מציּון as in Psa 134:3; Psa 20:3. בּנים לבניך instead of בּני בניך gives a designed indefiniteness to the first member of the combination. Every blessing the individual enjoys comes from the God of salvation, who has taken up His abode in Zion, and is perfected in participation in the prosperity of the holy city and of the whole church, of which it is the centre. A New Testament song would here open up the prospect of the heavenly Jerusalem. But the character of limitation to this present world that is stamped upon the Old Testament does not admit of this. The promise refers only to a present participation in the well-being of Jerusalem (Zac 8:15) and to long life prolonged in one's children's children; and in this sense calls down intercessorily peace upon Israel in all its members, and in all places and all ages.”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.