John 15:26

This glad tiding, like the one before it, speaks of the Messiah announcing to his people that Allāh would send a prophet after him. Here he refers to him as the Mu‘azzī and the Spirit of truth, who will teach people all the matters of their religion — all of which is set out in the Qur’ān. He will also testify on his behalf for good: that is, he will bear witness to the Messiah and report his account, the account of his mother, the Virgin Mary, and the harm he suffered from his people. The full account of the Messiah was recorded in the books of Prophetic Ḥadīth concerning the Messenger of Allāh in a way it was never recorded in the Christian books.

And in the Ḥadīth of the Prophet (peace and blessings of Allāh be upon him): no one has borne witness for the Messiah with a testimony heard by the general public except Muḥammad (peace and blessings of Allāh be upon him); for he made manifest the matter of the Messiah, bore witness to the truth concerning him, until the general people of the earth heard his testimony for him, and they knew that he confirmed the Messiah and exonerated him from what the Jews fabricated against him and from what the Christians exaggerated about him — so he is the one who testified to him with the truth (1).

Moreover, his saying: (whom I will send unto you) means: because of my supplication, my Lord will send him to you. It is not the Messiah who sends him from himself, because the sending of prophets is among the unique attributes of Allāh, Glorified and Exalted be He; therefore he says next: (which proceedeth from the Father).

(1) See Ibn al-Qayyim, Hidāyat al-Ḥayārā fī ajwibat al-Yahūd wa al- Naṣārā, p. 141.