World Wide Study Bible
a Bible passage
20. Saying, Arise, and take the young child and his mother, and go into the land of Israel—not to the land of Judea, for he was afterward expressly warned not to settle there, nor to Galilee, for he only went thither when he found it unsafe to settle in Judea but to "the land of Israel," in its most general sense; meaning the Holy Land at large—the particular province being not as yet indicated. So Joseph and the Virgin had, like Abraham, to "go out, not knowing whither they went," till they should receive further direction.
for they are dead which sought the young child's life—a common expression in most languages where only one is meant, who here is Herod. But the words are taken from the strikingly analogous case in Ex 4:19, which probably suggested the plural here; and where the command is given to Moses to return to Egypt for the same reason that the greater than Moses was now ordered to be brought back from it—the death of him who sought his life. Herod died in the seventieth year of his age, and thirty-seventh of his reign.