Psalms 68:9

Thou, O God, didst send a plentiful rain— What this shower was, is not by all agreed. Sometimes the Israelites were supplied with wells, and at other times God gave them miraculously water from rocks. The dropping of the heavens, in the foregoing verse, cannot be intended; because this plentiful rain is spoken of as a distinct thing from it. And the description of a shower, as it were voluntarily falling, distinguished it from a thunder-shower, occasioned by the violent bursting of the clouds. I think, therefore, that this shower relates to the manna and the quails which were rained down on them from heaven. Thus God told them, I will rain bread from heaven for you, Exodus 16:4. And the Psalmist puts them in mind, He commanded the clouds from above, and opened the doors of heaven, and rained down manna upon them to eat, and gave them of the corn of heaven; Psalms 78:23. He rained flesh also upon them as dust, and feathered fowls as the sand of the sea, Psalms 68:27. This may truly be called a kind of spontaneous shower; as both the manna and the quails offered themselves to their hands, without any pains or labour in the people to procure them. By this shower, says the sacred writer, thou didst confirm thine inheritance; (see Deuteronomy 32:9.) that is, "didst recruit and refresh thy people;" for they greatly needed it, as they were weary; i.e. tired and almost worn out with hunger, the hardships of which they bore with great impatience and murmuring. See Exodus 16:3.