For he remembered his holy promise The Psalmist again mentions the cause why God dealt so graciously with that people, and sustained them so tenderly, namely, that he might fulfill his promise; for he had entered into a covenant with Abraham, engaging to be the God of his seed. Nor did the prophets without cause teach so carefully as we find them doing, that the free covenant is the fountain whence the deliverance, and the continual welfare of the people flowed. Thereby the grace of God became better known, since what took place, so far from happening upon the sudden, and without anticipation, was only the fulfillment of what he had promised four hundred years before. God then, for ages previous to this, gave the light of his word of promise, that his grace and truth might be brought the more distinctly into view. For this reason the prophet again repeats, that God was not led from some new cause to deliver his people, but that his design in doing so was to prove the faithfulness of his covenant, and to give it effect; just as if a man should dig up from the ground a treasure which he had buried in it. Nor is it to be doubted, that the prophet aimed at leading the faith of his countrymen still farther, -- that his object was that their posterity might be persuaded beyond all doubt, that as God had then proved, in the experience of that generation, the sure and substantial truth of his promise delivered many hundred years before, so he would not be to them otherwise than their fathers had found him to be in times past. Accordingly, he signalises this promise by the epithet, holy, intimating, that after the death of Abraham it retained its virtue and efficacy unimpaired. God had spoken it to Abraham; but the force of the covenant died not with him. God continued to show himself faithful towards the posterity of the patriarch.

For he remembered - He was faithful to his promise made to Abraham, and did not forget his descendants in the hour of need. This is the statement made in Psalm 105:8-9; and to illustrate and confirm the faithfulness of God, this reference is made to the history of the Hebrew people. See the notes at those verses.

For he remembered his holy (x) promise, [and] Abraham his servant.
(x) Which he confirms to the posterity in whom after a sort the dead live and enjoy the promises.

For he remembered his holy promise,.... It was not owing to the goodness of this people, to their obedience to the divine will, to any worthiness or merit of theirs, that such signs and wonders were wrought for them in Egypt; and that they were brought out from thence in such a manner as they were; and were protected and so plentifully provided for in the wilderness; but it was owing to the grace and goodness of God, to his covenant and promise, which he sacredly and inviolably observed; the grace and covenant of God are the source and spring of all blessings of goodness; he is ever mindful of his covenant, and therefore sends meat to them that fear him, as he did to the Israelites, Psalm 111:5.
And Abraham his servant; or the promise he made to Abraham his servant; so the Targum,
"which "was" with Abraham his servant;''
that is, which holy word or promise was with Abraham, was spoken to him; and was with him, that he would give him and his seed the land of Canaan; and that though they should be afflicted long in Egypt, yet should come out from thence with great substance, Genesis 15:13, this he remembered, as he never forgets any promise of his, nor ever suffers his faithfulness to fail, nor his covenant to be broken. Hence it follows,

The reasons for these dealings: (1) God's faithfulness to His covenant, "His holy promise" of Canaan, is the fountain whence flowed so many acts of marvellous kindness to His people (compare Psalm 105:8, Psalm 105:11). Exodus 2:24 is the fundamental passage [HENGSTENBERG]. (2) That they might be obedient. The observance of God's commands by Abraham was the object of the covenant with him (Genesis 18:19), as it was also the object of the covenant with Israel, that they might observe God's statutes.
remembered . . . and Abraham--or, "remembered His holy word (that is, covenant confirmed) with Abraham."