Didache 7
About baptism, baptize this way. After you have said all these things beforehand, baptize in the name of the Father and of the Son and of the Holy Spirit, in living water.
If you do not have living water, baptize in other water; if you cannot use cold, use warm.
If you have neither, pour water on the head three times in the name of Father, Son, and Holy Spirit.
Before the baptism let the baptizer and the one being baptized fast, and any others who can. You are to tell the one being baptized to fast for one or two days beforehand.
Greek
Περὶ δὲ τοῦ βαπτίσματος, οὕτω βαπτίσατε· ταῦτα πάντα προειπόντες, βαπτίσατε εἰς τὸ ὄνομα τοῦ πατρὸς καὶ τοῦ υἱοῦ καὶ τοῦ ἁγίου πνεύματος ἐν ὕδατι ζῶντι. ἐὰν δὲ μὴ ἔχῃς ὕδωρ ζῶν, εἰς ἄλλο ὕδωρ βάπτισον· εἰ δ᾽ οὐ δύνασαι ἐν ψυχρῷ, ἐν θερμῷ. ἐὰν δὲ ἀμφότερα μὴ ἔχῃς, ἔκχεον εἰς τὴν κεφαλὴν τρὶς ὕδωρ εἰς ὄνομα πατρὸς καὶ υἱοῦ καὶ ἁγίου πνεύματος. πρὸ δὲ τοῦ βαπτίσματος προνηστευσάτω ὁ βαπτίζων καὶ ὁ βαπτιζόμενος καὶ εἴ τινες ἄλλοι δύνανται· κελεύεις δὲ νηστεῦσαι τὸν βαπτιζόμενον πρὸ μιᾶς ἢ δύο.