Euthyphro 12a9
Ζῆνα δὲ τὸν [θ’] ἔρξαντα καὶ ὃς τάδε πάντ᾽ ἐφύτευσεν
οὐκ ἐθέλει νεικεῖν· ἵνα γὰρ δέος ἔνθα καὶ αἰδώς.a9 θέρξαντα B: στέρξαντα T γρ. BW: ῥέξαντα Stobaeus Apostolius schol. ap. Cram. Anecd. Par. I, p. 399: θ᾽ ἕρξαντα B_2 W
b1 ἐθέλει νεικεῖν scripsi : ἐθέλεις εἰπεῖν B T ( νείκεσιν [small σ above the σ --Joel] schol. T) : ἐθέλειν εἰπεῖν W corr. B_2: ἐθέλειν εἴκειν schol. ap. Cram. l. c.
An interesting note from Burnett
Ζῆνα δὲ κτλ> . ‘Even he who was the author of all these things will not revile Zeus who wrought it; for where there is fear there is shame.’
See C.Q. viii. 235. The best-attested reading is certainly στέρξαντα (T and γρ. BW), but it does not seem to give any acceptable sense. The θέρξαντα of B (made into θ᾽ ἕρξαντα by W and B_2) will not do either; for ἔρδω never had a rough breathing. The ῥέξαντα of Stobaeus does not explain the corruptions in the MSS. I can see no way of accounting for the tradition except by supposing that Plato wrote τὸν ϝέρξαντα. He was, of course, quite familiar with the ‘digamma’, which was still written in many dialects in his day. It is true that there is no evidence of a > written ϝ > in epic verse, but it was still written in copies of e.g. Alcman, Sappho, and Alcaeus (cf. Ar. > Rhet. > 1367a 12), and there is one clear instance in the Alcman papyrus (ϝάνακτα), and others which can be certainly restored (Kühner-Blass, i, p. 78). Now this letter remained in use as a numeral (=6), and was written in Byzantine times so as to be hardly distinguishable from the ligature of στ (maunde Thompson, > Introd. to Greek and Latin Palaeography> , p. 91). That would account for στέρξαντα, while θέρξαντα would represent a mistake of a different kind. The reading ἐθέλει νεικεῖν (for ἐθέλεις εἰπεῖν BT) is also well attested by the ἐθέλειν εἴκειν of the scholium in Cramer’s > Anecdota > and the νείκεσιν in the margin of T. The first stage of corruption is shown by the ἐθέλειν εἰπεῖν of W.
The point about στέρξαντα seems very strong. στ = ϝ would sound like an error that might be seen elsewhere if this reasoning is correct.