This was done upon the sixth day, as was also the placing of Adam in paradise, though it be here mentioned after an account of the seventh day's rest: but what was said in general, Genesis 1:27, that God made man male and female is more distinctly related here, God caused the sleep to fall on Adam, and made it a deep sleep, that so the opening of his side might be no grievance to him: while he knows no sin, God will take care he shall feel no pain.
Related Commentaries of Genesis 2:21
Genesis 2:21
21 And the LORD God caused a deep sleep to fall upon Adam, and he slept: and he took one of his ribs, and closed up the flesh instead thereof;