Return, O Jehovah! how long? After having spoken in the language of complaint, Moses adds a prayer, That God, who had not ceased for a long time severely to punish his people, would at length be inclined to deal gently with them. Although God daily gave them in many ways some taste of his love, yet their banishment from the land of promise was a very grievous affliction; for it admonished them that they were unworthy of that blessed inheritance which he had appointed for his children. They could not fail often to remember that dreadful oath which he had thundered out against them, "Surely they shall not see the land which I sware unto their fathers, neither shall any of them that provoked me see it: But as for you, your carcases, they shall fall in this wilderness," (Numbers 14:23, 32.) [1] Moses, no doubt, combines that sore bondage which they had suffered in Egypt with their wanderings in the wilderness; and therefore he justly bewails their protracted languishing in the words how long? As God is said to turn his back upon us, or to depart to a distance from us, when he withdraws the tokens of his favor, so by his return we are to understand the manifestation of his grace. The word nchm, nacham, which we have translated be pacified, signifies to repent, and may therefore not improperly be explained thus: Let it repent thee concerning thy servants. According to the not unfrequent and well known phraseology of Scripture, God is said to repent, when putting away men's sorrow, and affording new ground of gladness, he appears as it were to be changed. Those, however, seem to come nearer the mind of the Psalmist who translate, Comfort thyself over thy servants; for God, in cherishing us tenderly, takes no less pleasure in us than does a father in his own children. Now that is nothing else than to be pacified or propitious, as we have translated it, to make the meaning the more obvious.

Footnotes

1 - "There is an ambiguity in kn, as it denotes either so or rightly Hence the interpretation is twofold; either so make us to know that we may cause a heart of wisdom to come,' i e., so instruct us that we may acquire a wise heart. Or, teach us to number our days rightly,' etc. LXX. give it another and distorted interpretation." -- Bythner

Return, O Lord - Come back to thy people; show mercy by sparing them. It would seem probable from this that the psalm was composed in a time of pestilence, or raging sickness, which threatened to sweep all the people away - a supposition by no means improbable, as such times occurred in the days of Moses, and in the rebellions of the people when he was leading them to the promised land.
How long? - How long shall this continue? How long shall thy wrath rage? How long shall the people still fall under thy hand? This question is often asked in the Psalm. Psalm 4:2; Psalm 6:3; Psalm 13:1-2; Psalm 35:17; Psalm 79:5, et al.
And let it repent thee - That is, Withdraw thy judgments, and be merciful, as if thou didst repent. God cannot literally "repent," in the sense that he is sorry for what he has done, but he may act "as if" he repented; that is, he may withdraw his judgments; he may arrest what has been begun; he may show mercy where it seemed that he would only show wrath.
Concerning thy servants - In respect to thy people. Deal with them in mercy and not in wrath.

Return, O Lord, how long? - Wilt thou continue angry with us for ever?
Let it repent thee - הנחם hinnachem, be comforted, rejoice over them to do them good. Be glorified rather in our salvation than in our destruction.

Return, O LORD, (m) how long? and let it repent thee concerning thy servants.
(m) Meaning, will you be angry?

Return, O Lord,.... Either from the fierceness of thine anger, according to Aben Ezra and Jarchi; of which complaint is made, Psalm 90:7, or unto us, from whom he had departed; for though God is everywhere, as to his being and immensity, yet, as to his gracious presence, he is not; and where that is, he sometimes withdraws it; and when he visits again with it, be may be said to return; and when he returns, he visits with it, and which is here prayed for; and designs a manifestation of himself, of his love and grace, and particularly his pardoning mercy; see Psalm 80:14.
how long? this is a short abrupt way of speaking, in which something is understood, which the affection of the speaker would not admit him to deliver; and may be supplied, either thus,
how long wilt thou be angry? God is sometimes angry with his people, which, when they are sensible of, gives them a pain and uneasiness they are not able to bear; and though it endures but for a moment, yet they think it a long time; see Psalm 30:5. Arama interprets it,
"how long ere the time of the Messiah shall come?''
or "how long wilt thou hide thyself?" when he does this, they are troubled; and though it is but for a small moment he forsakes them, yet they count it long, and as if it was for ever; see Psalm 13:1, or "how long wilt thou afflict us?" as the Targum; afflictions come from the Lord, and sometimes continue long; at least they are thought so by the afflicted, who are ready to fear God has forgotten them and their afflictions, Psalm 44:23, or "how long wilt thou defer help?" the Lord helps, and that right early, at the most seasonable time, and when difficulties, are the greatest; but it sometimes seems long first; see Psalm 6:3,
and let it repent thee concerning thy servants; men are all so, of right, by creation, and through the benefits of Providence; and many, in fact, being made willing servants by the grace of God; and this carries in it an argument for the petition: repentance does not properly belong to God; it is denied of him, Numbers 23:19, yet it is sometimes ascribed to him, both with respect to the good he has done, or promised, and with respect to the evil he has brought on men, or threatened to bring; see Genesis 6:6, and in the latter sense it is to be understood here; and intends not any change of mind or will in God, which cannot be; but a change of his dispensations, with respect to desertion, affliction, and the like; which the Targum expresses thus,
"and turn from the evil thou hast said thou wilt do to thy servants:''
if this respects the Israelites in the wilderness, and their exclusion from Canaan, God never repented of what he threatened; he swore they should not enter it, and they did not, only their children, excepting two persons: some render the words, "comfort thy servants" (f); with thy presence, the discoveries of thy love, especially pardoning grace, and by removing afflictions, or supporting under them.
(f) "consolare", Pagninus, Montanus, Vatablus.

(Compare Psalm 13:2).
let it repent--a strong figure, as in Exodus 32:12, imploring a change in His dealings.

The prayer for a salutary knowledge, or discernment, of the appointment of divine wrath is now followed by the prayer for the return of favour, and the wish that God would carry out His work of salvation and bless Israel's undertakings to that end. We here recognise the well-known language of prayer of Moses in Exodus 32:12, according to which שׁוּבה is not intended as a prayer for God's return to Israel, but for the turning away of His anger; and the sigh עד־מתי that is blended with its asks how long this being angry, which threatens to blot Israel out, is still to last. והנּהם is explained according to this same parallel passage: May God feel remorse or sorrow (which in this case coincide) concerning His servants, i.e., concerning the affliction appointed to them. The naming of the church by עבדיך (as in Deuteronomy 9:27, cf. Exodus 32:13 of the patriarchs) reminds one of Deuteronomy 32:36 : concerning His servants He shall feel compassion (Hithpa. instead of the Niphal). The prayer for the turning of wrath is followed in Psalm 90:14 by the prayer for the turning towards them of favour. In בּבּקר there lies the thought that it has been night hitherto in Israel. "Morning" is therefore the beginning of a new season of favour. In שׂבּענוּ (to which הסדּך is a second accusative of the object) is implied the thought that Israel whilst under wrath has been hungering after favour; cf. the adjective שׂבע in the same tropical signification in Deuteronomy 33:23. The supplicatory imperatives are followed by two moods expressive of intention: then will we, or: in order that we may rejoice and be glad; for futures like these set forth the intention of attaining something as a result or aim of what has been expressed just before: Ew. 325, a. בּכל־ימינוּ is not governed by the verbs of rejoicing (Psalm 118:24), in which case it would have been בּחיּינוּ, but is an adverbial definition of time (Psalm 145:2; Psalm 35:8): within the term of life allotted to us. We see from Psalm 90:15 that the season of affliction has already lasted for a long time. The duration of the forty years of wrath, which in the midst of their course seemed to them as an eternity, is made the measure of the reviving again that is earnestly sought. The plural ימות instead of ימי is common only to our Psalm and Deuteronomy 32:7; it is not known elsewhere to Biblical Hebrew. And the poetical שׁנות instead of שׁני, which also occurs elsewhere, appears for the first time in Deuteronomy 32:7. The meaning of ענּיתנוּ, in which ימות hcihw is specialized after the manner of a genitive, is explained from Deuteronomy 8:2., according to which the forty years' wandering in the wilderness was designed to humble (ענּות) and to prove Israel through suffering. At the close of these forty years Israel stands on the threshold of the Promise Land. To Israel all final hopes were closely united with the taking possession of this land. We learn from Genesis. 49 that it is the horizon of Jacob's prophetic benediction. This Psalm too, in Psalm 90:16-17, terminates in the prayer for the attainment of this goal. The psalmist has begun in Psalm 90:1 his adoration with the majestic divine name אדני; in Psalm 90:13 he began his prayer with the gracious divine name יהוה; and now, where he mentions God for the third time, he gives to Him the twofold name, so full of faith, אדני אלהינוּ. אל used once alternates with the thrice repeated על: salvation is not Israel's own work, but the work of Jahve; it therefore comes from above, it comes and meets Israel. It is worthy of remark that the noun פּעל occurs only in Deuteronomy in the whole Tra, and that here also of the gracious rule of Jahve, Psalm 32:4, cf. Psalm 33:11. The church calls the work of the Lord מעשׂה ידינוּ in so far as He executes it through them. This expression מעשׂה ידים as a designation of human undertakings runs through the whole of the Book of Deuteronomy: Deuteronomy 2:7; Deuteronomy 4:28; Deuteronomy 11:7; Deuteronomy 14:29; Deuteronomy 16:15; Deuteronomy 24:19; Deuteronomy 27:15; Deuteronomy 28:12; Deuteronomy 30:9. In the work of the Lord the bright side of His glory unveils itself, hence it is called הדר; this too is a word not alien at least to the language of Deuteronomy, Deuteronomy 33:17. Therein is made manifest נעם ה, His graciousness and condescension - an expression which David has borrowed from Moses in Psalm 27:4. יראה and יהי are optatives. כּוננה is an urgent request, imperat. obsecrantis as the old expositors say. With Waw the same thought is expressed over again (cf. Isaiah 55:1, וּלכוּ, yea come) - a simple, childlike anadiplosis which vividly reminds us of the Book of Deuteronomy, which revolves in thoughts that are ever the same, and by that very means speaks deeply to the heart. Thus the Deuteronomic impression of this Psalm accompanies us from beginning to end, from מעון to מעשׂה ידים. Nor will it now be merely accidental that the fondness for comparisons, which is a peculiarity of the Book of Deuteronomy (Deuteronomy 1:31, Deuteronomy 1:44; Deuteronomy 8:5; Deuteronomy 28:29, Deuteronomy 28:49, cf. Deuteronomy 28:13, Deuteronomy 28:44; Deuteronomy 29:17-18), is found again in this Psalm.

Return - To us in mercy. How long - Will it be before thou return to us? Repent thee - Of thy severe proceedings against us.