Psalms 81:5

He appointed it in Joseph for a testimony (R.V.): to bear continual witness to His care of Israel. when&c. Render, When he (i.e. God) went out against (or over) the land of Egypt, to execute judgement upon the Egyptians. See Exodus 11:4.

where I heard a language that I understood not The poet identifies himself with his nation and speaks in the name of Israel of old. It was an aggravation of their misery that they were toiling for masters whose language they could not understand. This meaning however, though Psalms 114:1 offers a parallel, is hardly adequate here. It is possible to render, The speech of one that I know not do I hear, and to regard the line as the words of the poet himself, introducing the divine oracle which follows. He suddenly breaks off, hearing a supernatural voice addressing him. Cp. Job 4:16; and for the introduction of God as the speaker, Psalms 60:6; Psalms 62:11. But it is difficult to see how the poet could speak of God as one whom I know not: the phrase must surely mean more than -strange," -unearthly": and it is preferable to render, The speech of one that I knew not did I hear. The Psalmist speaks in the person of Israel at the time of the Exodus. This he can do, since Israel of all time is one in virtue of the continuity of its national life. Israel then began to hearJehovah (such is the proper force of the tense in the original), Whom it had not yet learned to know as the self-revealing God of redemption, speaking to it in the wondrous works of the deliverance from Egypt. See Exodus 3:13; Exodus 6:2 ff., Exodus 6:7. The substance of the words which Israel heard in Egypt is given in the next verse, which contains God's decree for Israel's liberation from servitude: