Biblical Commentary on the Old Testament, by Carl Friedrich Keil and Franz Delitzsh, [1857-78], at sacred-texts.com
Psalms Chapter 128
The Family Prosperity of the God-Fearing Man
Just as Psa 127:1-5 is appended to Psa 126:1-6 because the fact that Israel was so surprised by the redemption out of exile that they thought they were dreaming, finds its interpretation in the universal truth that God bestows upon him whom He loves, in sleep, that which others are not able to acquire by toiling and moiling the day and night: so Psa 128:1-6 follows Psa 127:1-5 for the same reason as Psa 2:1-12 follows Psa 1:1-6. In both instances they are Psalms placed together, of which one begins with ashrê and one ends with ashrê. In other respects Psa 128:1-6 and Psa 127:1-5 supplement one another. They are related to one another much as the New Testament parables of the treasure in the field and the one pearl are related. That which makes man happy is represented in Psa 127:1-5 as a gift coming as a blessing, and in Psa 128:1-6 as a reward coming as a blessing, that which is briefly indicated in the word שׂכר in Psa 127:3 being here expanded and unfolded. There it appears as a gift of grace in contrast to the God-estranged self-activity of man, here as a fruit of the ora et labora. Ewald considers this and the preceding Psalm to be songs to be sung at table. But they are ill-suited for this purpose; for they contain personal mirrorings instead of petitions, and instead of benedictions of those who are about to partake of the food provided.
The כּי in Psa 128:2 signifies neither "for" (Aquila, κόπον τῶν ταρσῶν σου ὅτι φάγεσαι), nor "when" (Symmachus, κόπον χειρῶν σου ἐωθίων); it is the directly affirmative כּי, which is sometimes thus placed after other words in a clause (Psa 118:10-12, Gen 18:20; Gen 41:32). The proof in favour of this asseverating כּי is the very usual כּי עתּה in the apodoses of hypothetical protases, or even כּי־אז in Job 11:15, or also only כּי in Isa 7:9, Sa1 14:39; "surely then;" the transition from the confirmative to the affirmative signification is evident from Psa 128:4 of the Psalm before us. To support one's self by one's own labour is a duty which even a Paul did not wish to avoid (Act 20:34), and so it is a great good fortune (טוב לך as in Psa 119:71) to eat the produce of the labour of one's own hands (lxx , τοὺς καρποὺς τῶν πόνων, or according to an original reading, τοὺς πὸνους τῶν καρπῶν);
(Note: The fact that the τῶν καρπῶν of the lxx here, as in Pro 31:20, is intended to refer to the hands is noted by Theodoret and also by Didymus (in Rosenmuller): καρποὺς φησὶνῦν ὡς ἀπὸ μέρους τὰς χεῖρας (i.e., per synecdochen partis pro toto), τουτέστι τῶν πρακτικῶν σου δυνάμεων φάγεσαι τοὺς πόνους.)
For he who can make himself useful to others and still is also independent of them, he eats the bread of blessing which God gives, which is sweeter than the bread of charity which men give. In close connection with this is the prosperity of a house that is at peace and contented within itself, of an amiable and tranquil and hopeful (rich in hope) family life. "Thy wife (אשׁתּך, found only here, for אשׁתּך) is as a fruit-producing vine." פּריּה for פּרה, from פּרה = פּרי, with the Jod of the root retained, like בוכיּה, Lam 1:16. The figure of the vine is admirably suited to the wife, who is a shoot or sprig of the husband, and stands in need of the man's support as the vine needs a stick or the wall of a house (pergula). בּירכּתי ביתך does not belong to the figure, as Kimchi is of opinion, who thinks of a vine starting out of the room and climbing up in the open air outside. What is meant is the angle, corner, or nook (ירכּתי, in relation to things and artificial, equivalent to the natural ירכי), i.e., the background, the privacy of the house, where the housewife, who is not to be seen much out of doors, leads a quiet life, entirely devoted to the happiness of her husband and her family. The children springing from such a nobel vine, planted around the family table, are like olive shoots or cuttings; cf. in Euripides, Medea, 1098: τέκνων ἐν οἴκοις γλυκερὸν βλάστημα, and Herc. Fur. 839: καλλίπαις στέφανος. thus fresh as young layered small olive-trees and thus promising are they.
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.