قُل إِنَّما أَعِظُكُم بِواحِدَةٍ ۖ أَن تَقوموا لِلَّهِ مَثنىٰ وَفُرادىٰ ثُمَّ تَتَفَكَّروا ۚ ما بِصاحِبِكُم مِن جِنَّةٍ ۚ إِن هُوَ إِلّا نَذيرٌ لَكُم بَينَ يَدَي عَذابٍ شَديدٍ

Say, "I only advise you of one [thing] - that you stand for Allah, [seeking truth] in pairs and individually, and then give thought." There is not in your companion any madness. He is only a warner to you before a severe punishment.