Laudator Temporis Acti

Pindar, Pythian Odes 6.19-27 (tr. Anthony Verity):

In truth, by keeping it at your right hand,
you maintain the force of the principle
which they say Philyra's son once in the mountains
commended to the mighty son of Peleus, left alone in his care:
above all gods to revere the son of Cronus,
the deep-voiced lord of thunder and lightning,
and never to withhold the same honour from his parents
during their destined span of life.

σύ τοι σχεθών νιν ἐπιδέξια χειρός, ὀρθὰν
ἄγεις ἐφημοσύναν,        20
τά ποτ᾽ ἐν οὔρεσι φαντὶ μεγαλοσθενεῖ
Φιλύρας υἱὸν ὀρφανιζομένῲ
Πηλεΐδᾳ παραινεῖν· μάλιστα μὲν Κρονίδαν,
βαρυόπαν στεροπᾶν κεραυνῶν τε πρύτανιν,
θεῶν σέβεσθαι·        25
ταύτας δὲ μή ποτε τιμᾶς
ἀμείρειν γονέων βίον πεπρωμένον.

Philyra's son = Chiron the centaur; son of Peleus = Achilles; son of Cronus = Zeus.

Cf. Euripides, fragment 853 Kannicht (tr. Christopher Collard and Martin Cropp):

There are three virtues you should practise, child:
to honour the gods, the parents who begot you,
and the common laws of Greece. If you do these things,
you will always have good repute, the fairest of crowns.

τρεῖς εἰσιν ἀρεταὶ τὰς χρεών σ᾿ ἀσκεῖν, τέκνον,
θεούς τε τιμᾶν τούς τε φύσαντας γονῆς
νόμους τε κοινοὺς Ἑλλάδος· καὶ ταῦτα δρῶν
κάλλιστον ἕξεις στέφανον εὐκλείας ἀεί.

Isocrates, To Demonicus 16 (tr. David Mirhady), expands the list to four:

Fear the gods; honor your parents; respect your friends; obey the laws.

τοὺς μὲν θεοὺς φοβοῦ, τοὺς δὲ γονεῖς τίμα, τοὺς δὲ φίλους αἰσχύνου, τοῖς δὲ νόμοις πείθου.