Nisi Dominus Frustra

Psalm 127 (Vulgate Psalm 126) is one of 15 "Songs of Ascents" in the Book of Psalms, the only one among these attributed to Solomon (rather than David). In Jewish liturgy it is recited following Mincha between Sukkot and Shabbat Hagadol.

The text is divided in five verses. The first two express the notion that "without God, all is in vain", popularly summarized in Latin in the motto Nisi Dominus Frustra. The remaining three verses describe progeny as God's blessing. The Vulgate text, known from its incipit as Nisi Dominus, was set to music numerous times during the Renaissance and Baroque periods.

The translation of the psalm offers difficulties, especially in verses 2 and 4.

Jerome in a letter to Marcella (dated AD 384) laments that Origen's notes on this psalm were no longer extant, and discusses the various possible translations of לֶחֶם הָעֲצָבִים (KJV "bread of sorrows", after the panem doloris of Vulgata Clementina; Jerome's own translation was panem idolorum "bread of idols" following LXX), and of בְּנֵי הַנְּעוּרִֽים׃ (KJV "children of the youth", mistranslated in LXX as υἱοὶ τῶν ἐκτετιναγμένων "children of the outcast").

There are two possible interpretations of the phrase כֵּן יִתֵּן לִֽידִידֹו שֵׁנָֽא (KJV "for so he giveth his beloved sleep"): The word "sleep" may either be the direct object (as in KJV, following LXX and Vulgate), or an accusative used adverbially, "in sleep", i.e. "while they are asleep". The latter interpretation fits the context of the verse much better, contrasting the "beloved of the Lord" who receive success without effort, as it were "while they sleep" with the sorrowful and fruitless toil of those not so blessed, a sentiment paralleled by Proverbs 10:22 (KJV "The blessing of the LORD, it maketh rich, and he addeth no sorrow with it."). Keil and Delitzsch (1883) accept the reading of the accusative as adverbial, paraphrasing ""God gives to His beloved in sleep, i.e., without restless self-activity, in a state of self-forgetful renunciation, and modest, calm surrender to Him". However, A. F. Kirkpatrick in the Cambridge Bible for Schools and Colleges (1906) argues that while the reading "So he giveth unto his beloved in sleep" fits the context, the natural translation of the Hebrew text is still the one given by the ancient translators, suggesting that the Hebrew text as transmitted has been corrupted (which would make the LXX and Vulgate readings not so much "mistranslations" as correct translations of an already corrupted reading).English translations have been reluctant to emend the translation, due to the long-standing association of this verse with sleep being the gift of God.Abraham Cronbach (1933) refers to this as "one of those glorious mistranslations, a mistranslation which enabled Mrs. Browning to write one of the tenderest poems in the English language", referring to Elizabeth Barrett Browning's poem The Sleep, which uses "He giveth his beloved Sleep" as the last line of each stanza.

...
Wikipedia