Midrash sa Exodo 21:19: Sifra, Mekhilta DeRabbi Yishmael, Shemot Rabbah & Sifrei Devarim

2) "He has cursed his father and his mother": What is the intent of this? Because it is written (Shemoth 21:19) "And he who curses his father and his mother shall be put to death," I might think that he is not liable until he curses both of them; it is, therefore, written "He has cursed his father; ("He has cursed) his mother" — either one. A proselyte, then, is liable for (cursing) his mother, but not for (cursing) his father, (there being no "fatherhood" for a proselyte.) These are the words of R. Yossi Haglili. R. Akiva says: "He has cursed his father and his mother": One who is liable for (cursing) his father is liable for (cursing) his mother. One who is not liable for his father is not liable for his mother. R. Akiva concedes that a shtuki (an illegitimate child of unknown fatherhood) is liable for (cursing) his mother even though he is not liable for (cursing) his father.

(Exodus 21:18) "And if men quarrel": What is the intent of this section? It is written (Ibid. 21:24) "an eye for an eye," but sheveth (work-disability payment) and ripui (medical expenses) are not mentioned. It is, therefore, written (Ibid. 19) "If he arise, etc." Scripture comes to teach of (other payments) that are due him.

(Exodus 21:19) "If he arise and walk": I might think, even in his house; it is, therefore, written "al mishanto" (lit., "on his support'), i.e., on his own power.