Sir Richard C. Jebb, Commentary on Sophocles: Oedipus Tyrannus

[996] τὸ πατρῷον αἷμα ἑλεῖν is strictly ”to achieve （the shedding of） my father's blood. “ Classical Greek had no such phrase as αἶμα χεῖν or ἐκχεῖν in the sense of “to slay.” αἱρεῖν is to make a prey of, meaning “to slay,” or “to take,” according to the context （ Soph. Trach. 353 “Εὔρυτόν θ᾽ ἕλοι ι τὴν θ᾽ ὑψίπυργον Οἰχαλίαν）.” Cp. fr. 726 ἀνδρὸς αἶμα συγγενὲς ι κτείνας, which is even bolder than this, but similar, since here we might have had simply τὸν πατέρα ἑλεῖν, ”to slay my father “: Eur. Orest. 284 “εἴργασται δ᾽ ἐμοὶ ι μητρῷον αἶμα,” I have wrought the murder of a mother.