John 5:31

ἐὰν ἐγὼ μαρτυρῶ περὶ ἐμαυτοῦ, ἡ μαρτυρία μου οὐκ ἔστιν ἀληθής·

Rough Word-by-word:
If I I should testify concerning myself, the testimony of me not it is true,

Smooth Translation:
If I myself should testify concerning myself, my testimony is not true,

ἐὰν conditional conjunction "if"

ἐγὼ personal pronoun nominative 1st singular "I"

μαρτυρῶ verb present active subjunctive 1st singular from μαρτυρέω (I testify) "I should testify"

περὶ preposition with genitive "about, concerning"

ἐμαυτοῦ reflexive pronoun genitive 1st singular "myself"

ἡ definite article nominative singular feminine "the"

μαρτυρία noun nominative singular feminine "testimony"

μου pronoun genitive 1st singular "of me"

οὐκ adverb of negation "not"

ἔστιν verb present indicative 3rd singular from εἰμί (I am) "it [she] is"

ἀληθής adjective nominative singular feminine "true"