COMMENTARY on 17:105
A. Yusuf Ali:

Translation:
We sent down the (Qur´an) in Truth, and in Truth 2315 has it descended: and We sent you but to give Glad Tidings and to warn (sinners). 2316
Commentary:

2315  The Qur'an was sent down by Allah in Truth: it was not forged by any mortal. It has descended in Truth: it was not falsified or corrupted in the process of being communicated to mankind.

2316  The part of the Prophet was that of a Messenger: he was not responsible if the ungodly rejected it. He fulfilled his mission in promulgating and explaining it and leaving it as a legacy to the world.

 

Muhammad Asad:

Translation:
AND AS a guide towards the truth 126 have We bestowed this [revelation] from on high; with this [very] truth has it come down [unto thee, O Prophet]: 127 for We have sent thee but as a herald of glad tidings and a warner,
Commentary:
126  Lit., "with truth" or "in truth".
127  I.e., it has come down to man, through the Prophet, without any alteration, omission or addition.