God is the LORD, which hath shewed us light: bind the sacrifice with cords, even unto the horns of the altar.
God is the Lord, which hath showed us light - i:e., prosperity amidst the night of our adversity; alluding to the pillar of fire which shone by night for Israel (Exodus 13:21; Exodus 14:20; Nehemiah 9:12).
Bind the sacrifice with cords. "The sacrifice" - literally, the feast, hence, here the festive victim (Exodus 23:18; 2 Chronicles 30:22). At the feast of tabernacles especially there were many sacrificial victims offered him (29:13). Josephus' 'Antiquities,' 8: 14, 1, calls it 'a feast pre-eminently holy and great.' The sense is, since God is Yahweh, the faithful unchangeable fulfiller of His promises to His people, as he has now shown Himself, let us testify our gratitude by sacrifices.
Even unto the horns (or horn-like extremities in which the altar culminates)
Of the altar - on which the blood of the sacrifices was sprinkled.