This he ordained in Joseph for a testimony - literally, he placed this; that is, he appointed it. The word Joseph here stands for the whole Hebrew people, as in Psalms 80:1. See the notes at that verse. The meaning is, that the ordinance for observing this festival - the Passover - was to be traced back to the time when they were in Egypt. The obligation to observe it was thus enhanced by the very antiquity of the observance, and by the fact that it was one of the direct appointments of God in that strange and foreign land.
When he went out through the land of Egypt - Margin, against. Or rather, In his going out of the land of Egypt. Literally, In going upon the land of Egypt. The allusion is, undoubtedly, to the time when the Hebrews went out of the land of Egypt - to the Exodus; and the exact idea is, that, in doing this, they passed over a considerable portion of the land of Egypt; or, that they passed over the land. The idea in the margin, of its being against the land of Egypt, is not necessarily in the original.
Where I heard a language that I understood not - literally, “The lip, that is, the language, of one that I did not know, I heard.” This refers, undoubtedly, not to God, but to the people. The author of this psalm identifies himself here with the people - the whole nation - and speaks as if he were one of them, and as if he now recollected the circumstances at the time - the strange language - the foreign customs - the oppressions and burdens borne by the people. Throwing himself back, as it were, to that time (compare the notes at 1 Thessalonians 4:17) - he seems to himself to be in the midst of a people speaking a strange tongue - a language unintelligible to him - the language of a foreign nation. The Jews, in all their long captivity in Egypt - a period of four hundred years (see the notes at Acts 7:6) - preserved their own language apparently incorrupt. So far as appears, they spoke the same language, without change, when they came out of Egypt, that Abraham, Isaac, and Jacob had used. The Egyptian was entirely a foreign language to them, and had no affinity with the Hebrew.