He is daily merciful The Psalmist here repeats what he had already said, that the grace of God is a fountain of all blessings which can never be exhausted; and, therefore, while it is displayed towards the faithful, they not only have enough for the supply of their own wants, but are able also liberally to assist others. What he adds concerning their seed is variously expounded. That he is speaking of the children of the godly, there can be no doubt; and this is evident from the preceding verse. But when he says that they shall be for blessing, [1] some understand it as if he had said, They shall be the ministers of God's liberality: so that, according to them, the sense would be, that they shall follow the good example of their fathers in helping the poor, and in exercising liberality towards all men. But I fear that this exposition is too refined. Nor do I admit the interpretation which has been given by others, that the meaning is, that the grace of God shall be so signally manifested towards the children of the godly, that their names shall be employed in a form of prayer, when prosperity and success are prayed for. This mode of expression, I allow, is to be so understood in various places; but here, in my opinion, David designs nothing more than to extol the continuation of God's favor from the fathers to their children: as if he had said, God's blessing does not terminate with the death of the righteous man, but it extends even to his children. [2] And there is indeed no inheritance more certain to which our children may succeed us, than when God, receiving them in like manner into his fatherly favor, makes them partakers of his blessing.

Footnotes

1 - This is also the reading of the Septuagint, To spezma autou eis eulogian hestai

2 - Ainsworth reads, "And his seed are in the blessing," and understands the words as meaning, that the children of the just man "are in the blessing, or are appointed to the blessing, as the heirs thereof," Genesis 28:3; 1-Peter 3:9; and that they have still abundance, notwithstanding the liberality of their parents; for "the blessing of the Lord maketh rich," Proverbs 10:22.

He is ever merciful - Margin, as in Hebrew, "all the day." That is, it is his character; he is constantly in the habit of showing kindness. He does not do it at intervals, or only occasionally, but it is this that marks the character of the man. He is known by this. The word "merciful" here means kind, compassionate, benignant - and particularly in this respect, that he is willing to "lend" to others when he has the means.
And lendeth - The wicked man "borrows," but does not pay again Psalm 37:21; the righteous man "lends" to his neighbor.
And his seed is blessed - His children; his posterity, as the result of this conduct on his part. The effect of what he does passes over from him to them, conveying rich blessings to them.

He is ever merciful and lendeth - כל היום חונן kol haiyom chonen, "all the day he is compassionate." He is confirmed in the habit of godliness: he feels for the distresses of men, and is ready to divide and distribute to all that are in necessity.
And his seed is blessed - The preceding words were not spoken casually; his seed, his posterity, is blessed; therefore they are not abandoned to beg their bread.

He is ever merciful, and lendeth,.... He sympathizes with the poor in distress, and shows mercy to miserable objects; not only by words, but deeds: and this is his constant disposition and conduct; of which his lending, as well as giving to persons in necessity, is an instance; and which shows capacity, and is a proof of the observation of the psalmist, that such are never forsaken, nor left to beg their bread: so far from it, that they have to lend and give to others;
and his seed is blessed; either his seed sown, his alms deeds, which are blessed to him and his, and to them to whom he ministers, as Jarchi explains it; see 2-Corinthians 9:6; or rather his offspring, who are blessed of God with things temporal for his sake; and are blessed by men, who say of them, these are the posterity of such and such liberal persons.

his seed is blessed--literally, "for a blessing" (Genesis 12:2; Psalm 21:6). This position is still true as the rule of God's economy (1-Timothy 4:8; 1-Timothy 6:6).

Blessed - Not only with spiritual, but with temporal blessings.