An angel standing in the sun - Exceedingly luminous; every part of him emitting rays of light. From this representation, Milton has taken his description of Uriel, the angel of the sun. Paradise Lost, b. iii. l. 648 -
"The Archangel Uriel, one of the seven Who, in God's presence, nearest to his throne Stands ready at command and are his eyes That run through all the heavens, or down to the earth Bears his swift errands over moist and dry, Over sea and land."
All the fowls that fly - The carcasses of God's enemies shall be food for all the fowls of heaven. This is according to a Jewish tradition, Synopsis Sohar, p. 114, n. 25: "In the time when God shall execute vengeance for the people of Israel, he shall feed all the beasts of the earth for twelve months with their flesh and all the fowls for seven years." It is well known that both beasts and birds of prey are accustomed to frequent fields of battle, and live upon the slain.
And I saw an angel standing in the sun - A different angel evidently from the one which had before appeared to him. The number of angels that appeared to John, as referred to in this book, was very great, and each one came on a new errand, or with a new message. Everyone must be struck with the image here. The description is as simple as it can be; and yet as sublime. The fewest words possible are used; and yet the image is distinct and clear. A heavenly being stands in the blaze of the brightest of the orbs that God permits us here to see - yet not consumed, and himself so bright that he can be distinctly seen amidst the dazzling splendors of that luminary. It is difficult to conceive of an image more sublime than this. Why he has his place in the sun is not stated, for there does not appear to be anything more intended by this than to give grandeur and impressiveness to the scene.
And he cried with a loud voice - So that all the fowls of heaven could hear.
Saying to all the fowls that fly in the midst of heaven - That is, to all the birds of prey - all that feed on flesh - such as hover over a battlefield. Compare the notes on Isaiah 18:6; Isaiah 56:9. See also Jeremiah 7:33; Jeremiah 12:9; Ezekiel 39:4-20.
Come and gather yourselves together - All this imagery is taken from the idea that there would be a great slaughter, and that the bodies of the dead would be left unburied to the birds of prey.
Unto the supper of the great God - As if the great God were about to give you a feast - to wit, the carcasses of those slain. It is called “his supper” because he gives it; and the image is merely that there would be a great slaughter of his foes, as is specified in the following verse.