Verse 46

قُلْ إِنَّمَآ أَعِظُكُم بِوَٰحِدَةٍ أَن تَقُومُوا۟ لِلَّهِ مَثْنَىٰ وَفُرَٰدَىٰ ثُمَّ تَتَفَكَّرُوا۟ مَا بِصَاحِبِكُم مِّن جِنَّةٍ إِنْ هُوَ إِلَّا نَذِيرٌ لَّكُم بَيْنَ يَدَىْ عَذَابٍ شَدِيدٍ

Say; I only enlighten you regarding a single item; that you devote yourselves to God as a group or individually, then reflect. Your friend is not crazy. He is a warner to you before you face an ultimate suffering.