The Letter Qaf 50:45. Juz 26, page 520.
نَّحْنُ أَعْلَمُ بِمَا يَقُولُونَ ۖ وَمَآ أَنتَ عَلَيْهِم بِجَبَّارٍ ۖ فَذَكِّرْ بِٱلْقُرْءَانِ مَن يَخَافُ وَعِيدِ٤٥We are Best Aware of what they say, and thou (O Muhammad) art in no wise a compeller over them. But warn by the Qur'an him who feareth My threat.
Qaf 50:45, translated by Marmaduke Pickthall