In Daniel 6:22 Daniel says to the king "My God sent his angel, and he shut the mouths of the lions. They have not hurt me, because I was found innocent in his sight. Nor have I ever done any wrong before you, Your Majesty." Whether Daniel saw anything or not he certainly believed, and this is now in Scripture, that it was angels who keep the mouths of the lions shut so that they did not harm God's servant. No doubt angels often intervene so that God's servants are kept from harm.
Wesley comments on Daniel 6:22 "See the power of God over the fiercest creatures! See the care God takes of his faithful servants, especially when they are called to suffer for him! See how ready the angels are to minister to the heirs of salvation!"
Joseph Exell says "The text in Daniel suggests the whole doctrine of angel-ministration. That imperilled life guarded by a sentinel from heaven is no solitary spectacle. It has many parallels. There had been the ministration of angels before, as there has been a thousand times since."
