Exodus 21:15

ומכה אביו ואמו AND HE THAT SMITETH HIS FATHER OR HIS MOTHER [SHALL SURELY BE PUT TO DEATH] — Because Scripture has taught us that he who inflicts a wound upon his fellow-man is liable for damages (cf. Rashi on Exodus 21:24) but is not subject to death, it was compelled to state that he who inflicts a wound on his father or his mother is subject to the death penalty (Mekhilta). He is, however, not punishable with death except for a blow which causes a wound (Sanhedrin 85b). אביו ואמו means either his father or his mother (Mekhilta). מות יומת SHALL BE PUT TO DEATH — by strangulation (Mekhilta).

וּמַכֵּ֥ה אָבִ֛יו וְאִמּ֖וֹ מ֥וֹת יוּמָֽת׃ {ס}        

And he that smites his father, or his mother, shall be surely put to death.