27 Now he adds this also to the praises of God, that He led the Israelites out of Egypt enriched with silver and gold; because even they were then in such a condition, that they could not as yet despise the just and due, though temporal, reward of their toils....“He brought them forth also in silver and gold”: this too is a Scripture idiom; for “in silver and gold” is said for the same as if it had been said “with silver and gold: there was not one feeble person among their tribes:” in body, not in mind. This also was a great blessing of God, that in this necessity of removal there was no infirm person.
28. “Egypt was glad at their departing: for their fear fell upon them”; that is, the fear of the Hebrews upon the Egyptians. For “their fear” is not that with which the Hebrews feared, but that with which they were feared. Some one will say, how then were the Egyptians unwilling to dismiss them? Why did they let them go as if they expected them to return? Why did they lend them gold and silver, as to men who were to return, and to repay them, if “Egypt was glad at their departing”? But we must understand, after that final destruction of the Egyptians, and the terrible overthrow of the mighty pursuing army in the Red Sea, that the rest of the Egyptians feared lest the Hebrews should return, and with great ease crush the relics of them: illustrating what he had stated, that He made His people stronger than their enemies.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)