John Calvin Commentary Psalms 78:42

"They remember not his hand, Nor the day when he redeemed them from the adversary;" — Psalms 78:42 (ASV)

They remembered not his hand. The sacred writer still continues to rebuke the Israelites, for the simple remembrance of God’s benefits might have restrained them, had they not willfully and stubbornly forgotten whatever they had experienced. From this impious forgetfulness arise waywardness and all rebellion. The hand of God, as is well known, is by the figure of metonymy taken for his power.

In the deliverance of the chosen tribes from Egypt celebrated here, the hand of God was stretched out in a new and an unusual manner. And their impiety, against which the prophet now condemns, was made even more detestable by the fact that they accounted as nothing, or soon forgot, that which no length of time ought to have erased from their memory.

Further, he recounts certain examples of the power of God, which he calls first signs, and then miracles, (verse 43) so that, by recounting these, he may again rebuke the shameful stupidity of the people. By both these words he expresses the same thing; but in the second clause of the verse, the word miracles gives additional emphasis, implying that, by such strange and unheard-of events, the Egyptians had at that time been struck with such terror as ought not to have vanished so quickly from the minds of the Israelites.