We read here of an event that completes or supplements the picture given in Genesis 1:27. The Holy Spirit tells us in general terms in Genesis 1:27 that God created man on the sixth day. Now the Lord shows us that on this sixth day there was a lapse of time between the creation of the man and that of the woman. He now explains in more detail what happened then.
The Lord stirred up in Adam the desire for a helper that suited him. Now the time has come for Adam to receive that help. The Lord causes a deep sleep to fall upon Adam, as he would do later with Abraham (see Genesis 15:12). It is striking that Adam, because of this deep sleep, also does not consciously experience the Lord’s final work of creation. He has not seen with his own eyes that the Lord created the woman. He did not see that the Lord made Eve from a rib of his, even though he was already on earth. God’s whole work of creation escapes man’s consciousness. On this point we have to rely entirely on God’s revelation. We depend in everything on God’s speaking for the knowledge of the origin of creation.
21 So the LORD God caused a deep sleep to fall upon the man, and while he slept took one of his ribs and closed up its place with flesh.