John 3:30

ἐκεῖνον δεῖ αὐξάνειν, ἐμὲ δὲ ἐλαττοῦσθαι.

Rough Word-by-word:
that one he must to increase, me but to be made less important.

Smooth Translation:
Him, he must increase, but me be made less important.

Notes:
I found this construction difficult. I recognized the forms of the infinitives right away, but with no nominatives and only the verb δεῖ it was hard to put into English and include the accusatives.

ἐκεῖνον demonstrative accusative singular masculine "that one/ him"

δεῖ verb present active indicative 3rd singular from δεῖ (must) "he must"

αὐξάνειν present active infinitive from αὐξάνω ( I grow/I increase) "to increase"

ἐμὲ pronoun 1st accusative singular "me"

δὲ post positive conjunction "and/but"

ἐλαττοῦσθαι present passive infinitive from ἐλαττόω (I make less important) "to be made less important"