Enchiridion · §31

περὶ εὐσεβείας πρὸς θεοὺς ἴσθι ὅτι τὸ κυριώτατόν ἐστι τοῦτο, ὀρθὰς ὑπολήψεις περὶ αὐτῶν ἔχειν, ὡς ὄντων καὶ διοικούντων τὰ ὅλα καλῶς καὶ δικαίως, καὶ σαυτὸν εἰς τοῦτο κατατεταχέναι, τὸ πείθεσθαι αὐτοῖς καὶ εἴκειν πᾶσι τοῖς γινομένοις καὶ ἀκολουθεῖν ἑκόντα, ὡς ὑπὸ τῆς ἀρίστης γνώμης ἐπιτελουμένοις.οὕτω γὰρ οὔτε μέμψῃ ποτὲ θεοῖς οὔτε ἐγκαλέσεις ὡς ἀμελούμενος.

peri eusebeias pros theous isthi hoti to kuriōtaton esti touto, orthas hupolēpseis peri autōn echein, hōs ontōn kai dioikountōn ta hola kalōs kai dikaiōs, kai sauton eis touto katatetachenai, to peithesthai autois kai eikein pasi tois ginomenois kai akolouthein hekonta. houtō gar oute mempsē pote theois oute enkalesis hōs ameloumenos.

In matters of religion, know that the most essential thing is to hold correct judgments about the gods — that they exist, that they govern all things justly and well, and that your task is to place yourself in alignment with them: to obey, to yield to everything that happens, and to follow willingly what is brought to pass by the best intelligence. In this way you will never blame the gods or accuse them of neglecting you.

— Enchiridion 31

Source: Greek (Schenkl/Oldfather critical edition tradition) + Long 1877 English translation