He was not that Light, but [was sent] to bear witness of that Light.
Berean Study Bible (BSB) - John 1:8 >He himself was not the Light, but he came to testify about the Light.
Textus Receptus (TR) - John 1:8 >Οὐκ ἦν ἐκεῖνος τὸ φῶς, ἀλλ᾿ ἵνα μαρτυρήσῃ περὶ τοῦ φωτός.