To corroborate John Simpson’s answer to In “whosoever looks upon a woman to lust after her,” might that ‘to’ indicate a purpose clause?:
The Greek literally says Ἐγὼ δὲ λέγω ὑμῖν ὅτι πᾶς ὁ βλέπων γυναῖκα πρὸς τὸ ἐπιθυμῆσαι αὐτῆς, ἤδη ἐμοίχευσεν αὐτὴν ἐν τῇ καρδίᾳ αὑτοῦ, “towards the desiring of her”. That “towards” is indeed purposive, and it’s also not particularly Classical in taking an infinitive (though Classical Greek did use it as a purposive preposition: πρὸς τί “to what end?”, literally “towards what?”)
Classical usage of the infinitive with πρός is more literal: πῶς ἔχεις πρὸς τὸ ἐθέλειν ἂν ἰέναι ἄκλητος ἐπὶ δεῖπνον; “what is your attitude towards going to dinner uninvited?” But in this context, it looks clearly purposive to me.