Corpus Hippocratica, Precepts 4.10
“The way you address a patient requires some kind of a theory too. For, if you begin talking about payment, then something else occurs in every situation. You will leave the sick person with the kind of impression that you will abandon him and leave if there is no agreement and that you don’t care and you will not apply any relief in the present.
Therefore, you should not make an issue about payment. For we believe that this kind of thought is harmful when someone is sick, and even more so if the sickness is intense. For the swiftness of a sickness which does not provide ample time for changing your mind urges the one who practices medicine well not to seek profit but to think more of reputation. It is, therefore, better to rebuke patients who have been saved rather than to blackmail those who are facing ruin.”
παραινέσιος δ’ ἂν καὶ τοῦτ’ ἐπιδεηθείη τῆς θεωρίης· εἰ γὰρ ἄρξαιο περὶ μισθαρίων· ξυμβάλλει γάρ τι καὶ τῷ ξύμπαντι· τῷ μὲν ἀλγέοντι τοιαύτην διανόησιν ἐμποιήσεις τὴν, ὅτι [οὐκ] ἀπολιπὼν αὐτὸν πορεύσῃ μὴ ξυνθέμενος, καὶ ὅτι ἀμελήσεις, καὶ οὐχ ὑποθήσῃ τινὰ τῷ παρεόντι. ἐπιμελεῖσθαι οὖν οὐ δεῖ περὶ στάσιος μισθοῦ· ἄχρηστον γὰρ ἡγεύμεθα ἐνθύμησιν ὀχλεομένου τὴν τοιαύτην, πουλὺ δὲ μᾶλλον, ἢν ὀξὺ νόσημά τι· νούσου γὰρ ταχυτὴς καιρὸν μὴ διδοῦσα ἐς ἀναστροφὴν οὐκ ἐποτρύνει τὸν καλῶς ἰητρεύοντα ζητεῖν τὸ λυσιτελές, ἔχεσθαι δὲ δόξης μᾶλλον· κρέσσον οὖν σωζομένοισιν ὀνειδίζειν ἢ ὀλεθρίως ἔχοντας προμύσσειν.