Nahj al-Balāgha
Hadith 1779١٨٣. وَقَالَ (عليه السلام): مَا اخْتَلَفَتْ دَعْوَتَانِ إِلَّا كَانَتْ إِحْدَاهُمَا ضَلاَلَةً.
183. Amīr al-mu’minīn, peace be upon him, said: If there are two different calls then one (of them) must be towards misguidance.