For the poor shall not always be forgotten. The assertion that God will not forsake the poor and afflicted for ever, is a confirmation of the preceding sentence. By it he intimates, that they may indeed seem to be forsaken for a time. Let us, therefore, remember that God has promised his assistance to us, not in the way of preventing our afflictions, but of at length succouring us after we have been long subdued under the cross. David speaks expressly of hope or expectation, thereby to encourage us to prayer. The reason why God seems to take no notice of our afflictions is, because he would have us to awaken him by means of our prayers; for when he hears our requests, (as if he began but then to be mindful of us,) he stretches forth his powerful hand to help us. David again repeats that this is not done immediately, in order that we may persevere in hoping well, even although our expectations may not be instantly gratified.

For the needy - The poor; those who are dependent and helpless.
Shall not always be forgotten - That is, by God. He will interfere and save them by destroying their enemies. He will not suffer the wicked always to persecute and oppress the righteous. In due time he will vindicate his own cause; will deliver the oppressed and down-trodden, and will consign their oppressors to deserved punishment. This is as true now, in regard to all the oppressed and their oppressors, as it was in the time of the psalmist.
The expectation of the poor - Of the afflicted and the oppressed. The word "expectation" refers to their hope; their desire; their earnest looking for deliverance. In that state men naturally look for the divine interposition, and the psalmist says that in that they will not always be disappointed.
Shall not perish for ever - The word "not" is supplied here by our translators, but not improperly. It is thus supplied in the Targum, and in the Syriac, the Vulgate and the Greek. Such forms of construction are not uncommon. Compare Psalm 1:5; Deuteronomy 33:6. "The negative is repeated from the preceding member." - Michaelis.

The needy shall not alway be forgotten - The needy, and the poor, whose expectation is from the Lord, are never forgotten, though sometimes their deliverance is delayed for the greater confusion of their enemies, the greater manifestation of God's mercy, and the greater benefit to themselves.

For the needy shall not alway be forgotten: the expectation (i) of the poor shall [not] perish for ever.
(i) God does not promise to help us before we have felt the cross.

For the needy shall not always be forgotten,.... The people of God are poor and needy for the most part; they are so in things temporal, and they are poor in spirit, or in things spiritual, of which they are sensible; their needs are many, and frequently return; but God has provided a throne of grace for them to come to for help in time of need, and he will supply all their wants out of the fulness of grace in Christ; nor is he unmindful of them, and of his covenant with them; strictly speaking, they are never forgotten by him, being engraven on his hands, and set as a seal on his heart; but they sometimes seem to be so both to themselves and others, Psalm 42:3; and they may continue so long; God may seem for a long time to take no notice of them, but suffer them to lie under affliction and persecution; the holy city is trodden under foot forty two months, or one thousand two hundred and sixty days, that is, so many years; so long the witnesses prophesy in sackcloth, so long the church is in the wilderness, and so long will be the reign of antichrist, Revelation 11:2; but as great Babylon will come up in remembrance before God, and he will remember her sins, and render her double; the set time to favour his poor and needy will come, and he will arise and have mercy on them, and bring them into a glorious and comfortable state and condition;
the expectation of the poor shall not perish for ever; the negative particle, though not in the original text, is rightly supplied from the preceding clause, as it is by the Targum, Jarchi, Aben Ezra, and Kimchi, and as the sense requires; and the expectation of Christ's poor ones is not only a supply of grace here and eternal happiness hereafter; but they expect a glorious state of the church on earth, and that Christ will descend in person from heaven, and his tabernacle will be among men; and that they shall be kings and priests, and possess the kingdom, and reign with Christ a thousand years; and though these things may seem to be deferred, and their expectation put off to a length of time, yet it shall not perish for ever; there will be a performance of the things promised and expected.

(Compare Psalm 13:1-6).
the needy--literally, "poor," as deprived of anything; hence miserable.
expectation of the poor--or, "meek," "humble," made so by affliction.