6 But let us hear what they next confess: “we have sinned with our fathers: we have done amiss, and dealt wickedly”. What means “with our fathers”?...“Our fathers,” he says, “regarded not Your wonders in Egypt”; and many other things also, he does relate of their sins. Or is, “we have sinned with our fathers,” to be understood as meaning, we have sinned like our fathers, that is, by imitating their sins? If it be so, it should be supported by some example of this mode of expression: which did not occur to me when I sought on this occasion an instance of any one saying that he had sinned, or done anything, with another, whom he had imitated by a similar act after a long interval of time. What means then, “Our fathers understood not Your wonders;” save this, they did not know what You wished to convince them of by these miracles? What indeed, save life eternal, and a good, not temporal, but immutable, which is waited for only through endurance? For this reason they impatiently murmured, and provoked, and they asked to be blessed with present and fugitive blessings, “Neither were they mindful of the greatness of Your mercy.” He reproves both their understanding and memory. Understanding there was need of, that they might meditate unto what eternal blessings God was calling them through these temporal ones; and of memory, that at least they might not forget the temporal wonders which had been wrought, and might faithfully believe, that by the same power which they had already experienced, God would free them from the persecutions of their enemies; whereas they forgot the aid which He had given them in Egypt, by means of such wonders, to crush their enemies. “And they provoked, as they went up to the sea, even to the Red Sea.” We ought especially to notice how the Scripture does censure the not understanding that which ought to have been understood, and the not remembering that which ought to have been remembered; which men are unwilling to have ascribed to their own fault, for no other reason than that they may pray less, and be less humble unto God, in whose sight they should confess what they are, and might by praying for His aid, become what they are not. For it is better to accuse even the sins of ignorance and negligence, that they may be done away with, than to excuse them, so that they remain; and it is better to clear them off by calling upon God, than to clench them by provoking Him.
He adds, that God acted not according to their unbelief. “Nevertheless,” he says, “He saved them for His Name's sake: that He might make His power to be known”: not on account of any deservings of their own.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)