10 As the Prophet testifies, “The poor man cried, and the Lord heard him”. He teaches you how you may be heard. Therefore are you not heard, because you are rich. Lest haply thou say, you cried and wast not heard, hear wherefore; “The poor man cried, and the Lord heard him.” As poor cry thou, and the Lord hears. And how shall I cry as poor? By not, if you have anything, presuming therefrom upon your own strength: by understanding that you are needy; by understanding that so long are you poor, as you have not Him who makes you rich.
But how did the Lord hear him? “And saved him out of all his troubles.” And how saves He men out of all their troubles? “The Angel of the Lord shall send round about them that fear Him, and shall deliver them”. So it is written, brethren, not as some bad copies have it, “The Lord shall send His Angel round about them that fear Him, and He shall deliver them:” but thus, “The Angel of the Lord shall send round about them that fear Him, and shall deliver them.” Whom called He here the Angel of the Lord, who shall send round about them that fear Him, and shall deliver them?
Our Lord Jesus Christ Himself is called in Prophecy, the Angel of the great Counsel, the Messenger of the great Counsel; so the Prophets called Him. Even He then, the Angel of the great Counsel, that is, the Messenger, shall send unto them that fear the Lord, and shall deliver them. Fear not then lest you be hid: wheresoever you have feared the Lord, there does that Angel know you, who shall send to succour you, and shall deliver you.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)