Matthew 2:13

‘And when they were departed, behold, an angel of the Lord appears to Joseph in a dream, saying, “Arise and take the young child and his mother, and flee into Egypt, and you must remain there until I tell you, for Herod will seek the young child to destroy him.” '

Then as soon as they had departed the angel of the Lord approached Joseph, again in a dream (compare Matthew 1:20), and bade him ‘Arise, and take the young child and his mother, and flee into Egypt, and you must remain there until I tell you, for Herod will seek the young child to destroy him.” Note the emphasis on the young child. The mother is again secondary. (It is not ‘take your wife and child'). And they were to flee to Egypt and remain there until they were told further what to do. They were now under divine supervision. And the reason for the urgency is then explained, Herod will seek the young child to destroy Him.

We should note here the reason why Herod was seeking to destroy Him. It was because He was ‘the King of the Jews'. This has not only been stated by the Magi but has also been the burden of Matthew's presentation up to this point. So the King of the Jews was now to take refuge in Egypt where Israel had once taken refuge so long before. This is not surprising. Egypt regularly acted as an asylum for threatened Jews, and there were in fact at this time already over a million Jews in Egypt.