Rashi on Leviticus
כל נפש מכם NO SOUL OF YOU [SHALL EAT BLOOD] — This is stated in addition to v. 10 to admonish the adults about their young children (that they should not permit them blood to eat — for “no soul” shall eat blood) (Sifra, Acharei Mot, Section 7 6; Yevamot 114a).
Chizkuni
על כן אמרתי, “therefore I have said, etc;” this is a reference to Leviticus 3,17.