σοὶ μὲν παιδιὰν τοῦτ' εἶναι, ἐμοὶ δὲ θάνατον → This is sport to you but death to me (Aristotle, Eudemian Ethics 1243a20)
dat. sg. de ἑός.
ἑῷ: dat. sing. к ἑός.