Psalm 81:5

New English Translation

⁵He decreed it as a regulation in Joseph,
when he attacked the land of Egypt.^[a]
I heard a voice I did not recognize.^[b]

Psalm 81:5 tn Heb “in his going out against the land of Egypt.” This apparently refers to the general time period of Israel’s exodus from Egypt. The LXX reads, “from Egypt,” in which case “Joseph” (see the preceding line) would be the subject of the verb, “when he [Joseph = Israel] left Egypt.”
Psalm 81:5 tn Heb “a lip I did not know, I heard.” Here the term “lip” probably stands for speech or a voice. Apparently the psalmist speaks here and refers to God’s voice, whose speech is recorded in the following verses.

Psalm 81:5

New International Version

⁵When God went out against Egypt,^(A)
he established it as a statute for Joseph.

I heard an unknown voice say:^(B)

⁵This He established in Joseph as a testimony,
When He went throughout the land of Egypt,
^(A)Where I heard a language I did not understand.

⁵他去攻擊埃及地的時候，在約瑟中間立此為證。我在那裡聽見我所不明白的言語，

New English Translation (NET)

New International Version (NIV)