Psalms 81:5

This he ordained in Joseph for a testimony,.... That is, this law concerning the blowing of trumpets on the new moon, and the keeping the solemn feast at the full of the moon, was made to be observed by all Israel, who are meant by Joseph, for a testimony of God's good will to them, and of their duty and obedience to him:

when he went out through the land of Egypt, or "over it" b; which some understand of Joseph, who is said to go over all the land of Egypt, to gather in provision against the seven years of famine,

Genesis 41:45 and Jarchi says that his deliverance from prison was at the beginning of the year, and was advanced in Pharaoh's court: and the meaning is, either "when he", the Lord, "went out against the land of Egypt", so Arama, in order to slay their firstborn; and when he passed over Israel, and saved them; marched through the land in his indignation, and went forth for the salvation of his people,

Exodus 11:4 then was the ordinance of the passover appointed: or when Israel went out of Egypt, designed by Joseph, some little time after, while in the wilderness, and dwelling in tents, the feast of tabernacles was instituted; but rather this shows that the feast of passover is before meant, which was instituted at the time of Israel's going out of Egypt, and was the solemn feast day ordained for a statute, law and testimony in Israel; and that the new moon, or month rather, on which the trumpet was to be blown, was the month Abib, the beginning of months, by an ordinance of God, Exodus 12:2

where I heard a language that I understood not; here the prophet represents the people of Israel in Egypt; though the Septuagint, Vulgate Latin, Syriac, and Arabic versions, read,

he heard, and he understood not and the language is either the voice of God out of the fire, which before was never heard in this unusual manner, nor understood, Deuteronomy 5:24 or the speech of Moses, who had Aaron for his mouth and spokesman; or rather the Egyptian language, which was not understood by the Israelites without an interpreter,

Genesis 42:23 which sense is confirmed by Psalms 114:1, and this is mentioned as an aggravation of their affliction in Egypt; see Jeremiah 5:15.

b בצאתו על ארץ "in ipsum exeundo", Montanus; "cum exiret ipse super terram", Pagninus.