John 5:47

εἰ δὲ τοῖς ἐκείνου γράμμασιν οὐ πιστεύετε, πῶς τοῖς ἐμοῖς ῥήμασιν πιστεύσετε;

Rough Word-by-word:
if and the of him writings not you all believe, how the by me words will you believe?

Smooth Translation:
And if you do not believe his writings, how will you believe the words by me?

εἰ conditional particle "if"

δὲ post positive conjunction "and"

τοῖς definite article dative plural neuter "the"

ἐκείνου pronoun genitive plural masculine "of him"

γράμμασιν noun dative plural neuter "writings"

οὐ adverb of negation "not"

πιστεύετε verb present active indicative 2nd plural from πιστεύω (I believe) "you all believe"

πῶς interrogative pronoun "how"

τοῖς definite article dative plural neuter "the"

ἐμοῖς pronoun dative plural neuter "by me"

ῥήμασιν noun dative plural neuter "words"

πιστεύσετε verb future active indicative 2nd plural from πιστεύω (I believe) "you all will believe"