Leviticus 20:9

אביו ואמו קלל HE HATH CURSED HIS FATHER OR HIS MOTHER — These apparently redundant words are intended to include as subject to the death penalty one who curses his parents after their death (Sanhedrin 85b). דמיו בו HIS BLOOD IS UPON HIM — This implies execution by stoning; similarly wherever the expressions דמיו בו or דמיהם בם occur. We learn this Halachic rule from the case of אוב and ידעוני of whom Scripture expressly states, (v. 27) [“they shall surely be put to death], they shall overwhelm them with stones, their blood is upon them (דמיהם בם)” (Sifra, Kedoshim, Chapter 10 7; cf. Sanhedrin 54a; Keritot 5a). But according to the literal sense of the passage it means the same as the expression דמו בראשו (Joshua 2:19): “[whosoever shall go out of the doors of thy house into the street his blood shall be upon his own head] (דמו בראשו)” where the meaning is: No one deserves punishment on account of his death except himself, for he brought it upon himself that he should be killed (i. e. it was his own fault).

כִּֽי־אִ֣ישׁ אִ֗ישׁ אֲשֶׁ֨ר יְקַלֵּ֧ל אֶת־אָבִ֛יו וְאֶת־אִמּ֖וֹ מ֣וֹת יוּמָ֑ת אָבִ֧יו וְאִמּ֛וֹ קִלֵּ֖ל דָּמָ֥יו בּֽוֹ׃

For everyone that curses his father or his mother shall be surely put to death: he has cursed his father or his mother; his blood shall be upon him.