When the morning stars sang together. The stars generally, or the actual stars visible on the morn of creation, are probably meant. They, as it were, sang a song of loud acclaim on witnessing the new marvel.
Their priority to the earth is implied, since they witness its birth. Their song is, of course, that silent song of sympathy, whereof Shakespeare speaks when he says, "Each in its motion like an angel sings" ('Merchant of Venice,' act 5.
sc. 1). And all the sons of God shouted for joy. "The sons of God" here must necessarily be the angels (see Job 1:6; Job 2:1), since there were no men as yet in existence. They too joined in the chorus of sympathy and admiration, perhaps lifting up their voices (Revelation 5:11, Revelation 5:12), perhaps their hearts only, praising the Creator, who had done such marvellous things.