5. a testimony—The feasts, especially the passover, attested God's relation to His people.
Joseph—for Israel (Ps 80:1).
went out through—or, "over," that is, Israel in the exodus.
I heard—change of person. The writer speaks for the nation.
language—literally, "lip" (Ps 14:1). An aggravation or element of their distress that their oppressors were foreigners (De 28:49).