Bless the LORD, you his angels, that excel in strength, that do his commandments, hearkening unto the voice of his word.
Read Chapter 103
Augustine of Hippo
AD 430
24. "Bless ye the Lord, ye Angels of His, ye that are mighty in strength: ye that fulfil His word" (ver. 20). By the word of God, then, thou art not righteous, nor faithful, unless when thou dost it. "Ye that are mighty in strength, ye that fulfil His commandment, and hearken unto the voice of His words."
His angels. You who have executed the orders of God for our delivery, help us to return him thanks. (Calmet)
Hearkening. Literally, "to hear "(Haydock) or that all may learn to obey God's mandates when they perceive how carefully the angels put them in execution. (Berthier)