Exodus 11:4

And Moses said,.... To Pharaoh before he left him, when he had told him he should see his face no more; for the three preceding verses are to be read in a parenthesis, being placed here by the historian, as giving some light to this last discourse and transaction between Moses and Pharaoh:

thus saith the Lord, about midnight will I go out into the midst of Egypt; perhaps to the capital and metropolis of it, which might stand in the midst of it, as usually does the royal city; or it may only signify that he would go into the very heart of it, and steer his course all around in every part and quarter of it, slaying the firstborn everywhere in all towns and cities throughout the kingdom, as follows; in order to which he is said to go out, either from the place where Moses used to go and pray to him, and where he met him and gave him his orders and instructions, or out of the land of Goshen, where he dwelt among the Israelites; or rather it only signifies the manifestation of himself in some work and action of his, the exertion of his power in inflicting punishment for sin: thus God is sometimes said to go forth out of his place when he is about to exercise judgment in the earth; for this must be understood consistent with his omnipresence, see Isaiah 26:21 and this was to be done about midnight, the middle of the night following the present day, which was the fourteenth of the month of Abib or Nisan; it was in the morning of that day Moses had this discourse with Pharaoh, and in the evening of it the passover was kept, and about the middle of the night the firstborn were slain, as follows.