Sforno on Genesis 9:4/ספורנו על בראשית ט׳:ד׳

1אך בשר בנפשו, but the flesh of living animals, while its life-force is still inside it,

2 i.e. this life-force is equivalent to its blood; you must neither eat its flesh nor its blood,

3לא תאכלו, only in that state must you not eat it; once the blood has left the body, gentiles are allowed to eat blood.