Psalms 81:5

This He ordained in Joseph, this one tribe here representing the entire nation, for a testimony, when He went out through the land of Egypt, in preparing for the exodus of His people; for from that time dated the personal intercourse of Jehovah with His people; where I heard a language that I understood not, the psalmist speaking in the name of Israel, states that the fact of a strange language in the mouth of their oppressors in Egypt increased the burden of their slavery. The mention of these facts agreed with the object of the Hebrew festivals, which were to bring the great deeds of God to the remembrance of all believers. The Lord Himself now takes up the strain of the hymn.