Biblical Commentary on the Old Testament, by Carl Friedrich Keil and Franz Delitzsh, [1857-78], at sacred-texts.com
The Consolation of Divine Protection
This song of degrees is the only one that is inscribed שׁיר למעלות and not שׁיר המעלות. The lxx, Targum, and Jerome render it as in the other instances; Aquila and Symmachus, on the contrary, ᾠδὴ (ᾆσμα) εἰς τάς ἀναβάσεις, as the Midrash Sifrı̂ also mystically interprets it: Song upon the steps, upon which God leads the righteous up into the other world. Those who explain המעלות of the homeward caravans or of the pilgrimages rightly regard this למעלות, occurring only once, as favouring their explanation. But the Lamed is that of the rule or standard. The most prominent distinguishing mark of Psa 121:1-8 is the step-like movement of the thoughts: it is formed למּעלות, after the manner of steps. The view that we have a pilgrim song before us is opposed by the beginning, which leads one to infer a firmly limited range of vision, and therefore a fixed place of abode and far removed from his native mountains. The tetrastichic arrangement of the Psalm is unmistakeable.
Apollinaris renders as meaninglessly as possible: ὄμματα δενδροκόμων ὀρέων ὑπερεξετάνυσσα - with a reproduction of the misapprehended ἦρα of the lxx. The expression in fact is אשּׂא, and not נשׂאתי. And the mountains towards which the psalmist raises his eyes are not any mountains whatsoever. In Ezekiel the designation of his native land from the standpoint of the Mesopotamian plain is "the mountains of Israel." His longing gaze is directed towards the district of these mountains, they are his ḳibla, i.e., the sight-point of his prayer, as of Daniel's, Dan 6:11. To render "from which my help cometh" (Luther) is inadmissible. מאין is an interrogative even in Jos 2:4, where the question is an indirect one. The poet looks up to the mountains, the mountains of his native land, the holy mountains (Psa 133:3; Psa 137:1; Psa 125:2), when he longingly asks: whence will my help come? and to this question his longing desire itself returns the answer, that his help comes from no other quarter than from Jahve, the Maker of heaven and earth, from His who sits enthroned behind and upon these mountains, whose helpful power reaches to the remotest ends and corners of His creation, and with (עם) whom is help, i.e., both the willingness and the power to help, so that therefore help comes from nowhere but from (מן) Him alone. In Psa 121:1 the poet has propounded a question, and in Psa 121:2 replies to this question himself. In Psa 121:3 and further the answering one goes on speaking to the questioner. The poet is himself become objective, and his Ego, calm in God, promises him comfort, by unfolding to him the joyful prospects contained in that hope in Jahve. The subjective אל expresses a negative in both cases with an emotional rejection of that which is absolutely impossible. The poet says to himself: He will, indeed, surely not abandon thy foot to the tottering (למּוט, as in Psa 66:9, cf. Psa 55:23), thy Keeper will surely not slumber; and then confirms the assertion that this shall not come to pass by heightening the expression in accordance with the step-like character of the Psalm: Behold the Keeper of Israel slumbereth not and sleepeth not, i.e., He does not fall into slumber from weariness, and His life is not an alternate waking and sleeping. The eyes of His providence are ever open over Israel.
That which holds good of "the Keeper of Israel" the poet applies believingly to himself, the individual among God's people, in Psa 121:5 after Gen 28:15. Jahve is his Keeper, He is his shade upon his right hand (היּמין as in Jdg 20:16; Sa2 20:9, and frequently; the construct state instead of an apposition, cf. e.g., Arab. jânbu 'l-grbı̂yi, the side of the western = the western side), which protecting him and keeping him fresh and cool, covers him from the sun's burning heat. על, as in Psa 109:6; Psa 110:5, with the idea of an overshadowing that screens and spreads itself out over anything (cf. Num 14:9). To the figure of the shadow is appended the consolation in Psa 121:6. הכּה of the sun signifies to smite injuriously (Isa 49:10), plants, so that they wither (Psa 102:5), and the head (Jon 4:8), so that symptoms of sun-stroke (Kg2 4:19, Judith 8:2f.) appears. The transferring of the word of the moon is not zeugmatic. Even the moon's rays may become insupportable, may affect the eyes injuriously, and (more particularly in the equatorial regions) produce fatal inflammation of the brain.
(Note: Many expositors, nevertheless, understand the destructive influence of the moon meant here of the nightly cold, which is mentioned elsewhere in the same antithesis. Gen 31:40; Jer 36:30. De Sacy observes also: On dit quelquefois d'un grand froid, comme d'un grand chaud, qu'il est brulant. The Arabs also say of snow and of cold as of fire: jaḥrik, it burns.)
From the hurtful influences of nature that are round about him the promise extends in Psa 121:7-8 in every direction. Jahve, says the poet to himself, will keep (guard) thee against all evil, of whatever kind it may be and whencesoever it may threaten; He will keep thy soul, and therefore thy life both inwardly and outwardly; He will keep (ישׁמר־, cf. on the other hand ישׁפּט־ in Psa 9:9) thy going out and coming in, i.e., all thy business and intercourse of life (Deu 28:6, and frequently); for, as Chrysostom observes, ἐν τούτοις ὁ βίος ἅπας, ἐν εἰσόδοις καὶ ἐξόδοις, therefore: everywhere and at all times; and that from this time forth even for ever. In connection with this the thought is natural, that the life of him who stands under the so universal and unbounded protection of eternal love can suffer no injury.