Divine revelation as the source of warning

قُلْ إِنَّمَآ أُنذِرُكُم بِٱلْوَحْىِ ۚ وَلَا يَسْمَعُ ٱلصُّمُّ ٱلدُّعَآءَ إِذَا مَا يُنذَرُونَ

Say, "I only warn you by revelation." But the deaf do not hear the call when they are warned.