Psalms 81:5

This he ordained in Joseph— A solemn charge, which he laid on Joseph when he marched out in the face of the land of Egypt. I heard a language I did not know: Psalms 81:6. I removed, &c. God is asserting his title to their obedience, from three very remarkable providences towards them: his saving them when they cried to him in their distress, ver.7 whether in Egypt, or at the Red Sea; his speaking to them on mount Sinai, from the midst of thunder, where he was hid in darkness; and his giving them water out of the rock. He begins with saying he had heard a language which he did not understand. That is, (as some explain it) they did not speak the true genuine Hebrew, but a corrupted language, perhaps, with a mixture of Egyptian. This (according to them) is said to shew that contemptible state of barbarism to which they were reduced in Egypt before he rescued them. Others, by this language, understand the voice of God, which the Israelites soon after their departure from Egypt heard from mount Sinai, to their great astonishment, as having never before been acquainted with it: and, accordingly, what the purport of that voice or language was, we see in the following verses, even to the end of the psalm, where God is introduced as speaking in his own person, and instructing the Israelites concerning the design of this solemnity; and withal complaining of their forgetfulness of his benefits, in giving them so great a deliverance from Egyptian slavery.