Adam Clarke on Psalms 81:5

I heard a language I understood not - This passage is difficult. Who heard? And what was heard? All the Versions, except the Chaldee, read the pronoun in the third person, instead of the first. "He heard a language that he understood not." And to the Versions Kennicott reforms the text, שפת לא ידעה ישמע sephath lo yadah yisma; "a language which he did not understand he heard." But what was that language? Some say the Egyptian; others, who take Joseph to signify the children of Israel in general, say it was the declaration of God by Moses, that Jehovah was the true God, that he would deliver their shoulder from their burdens, and their hands from the pots - the moulds and furnaces in which they formed and baked their brick.