This comes from Jerome’s commentary on Daniel, his comments on verses 16 and 17.
Verses 16, 17. “And I heard the voice of a man in the midst of the Ulai, and he cried out and said: ‘Gabriel, make this vision intelligible (Vulgate: make this man to understand the vision). And he came and stood near to where I was standing.” The Jews claim that this man who directed Gabriel to explain the vision to Daniel was Michael [himself]. Quite appropriately it was Gabriel, who has been put in charge of battles, to whom this duty was assigned, inasmuch as the vision had to do with battles and contests between kings and even between kingdoms themselves. For Gabriel is translated into our language as “the strength of, or the mighty one of, God.” And so at that time also when the Lord was about to be born and to declare war against the demons and to triumph over the world, Gabriel came to Zacharias and to Mary (Luke 1). And then we read in the Psalms concerning the Lord in His triumph: “Who is this king of glory? The Lord strong and mighty, the Lord mighty in battle; He is the King of glory” (Ps. 23:8=24:8). But whenever it is medicine or healing that is needed, it is Raphael who is sent, for his name is rendered as “the healing of,” or “the medicine of God” that is, if one cares to accept the authority of the Book of Tobias. And then, when favorable promises are made to the people, and hilasmos, which we might render as “propitiation” or “expiation,” is the thing required , then it is Michael who is directed to go, for his name means, “Who is like God?” Of course the significance of the name indicates the fact that the only true remedy is to be found in God.
 From Archer, 88: “The point of this quotation seems to be that the Hebrew word for “mighty” is gibbowr, from the root of which comes the gabri- of Gabriel.”