Explaining the Misguidance in Distinguishing Between a Single-Narrator Report and a Mass-Transmitted Report

The Shaykh : ... Here we now enter into the core of explaining the misguidance in distinguishing between a report from a single narrator (ahad) and a mass-transmitted report (mutawatir).
It is beneficial to mention a story that occurred in Yemen concerning Abu Musa and Mu'adh. Mu'adh was calling to Islam, as we mentioned, and so was his companion Abu Musa al-Ash'ari. Mu'adh visited Abu Musa and found a man there who was bound and a prisoner. He said: "What is the matter with this man?" They said: "He has apostatized from his religion, and so many days have passed since he did not repent to Allah the Exalted." He was riding his mount, so he said: "By Allah, I will not dismount until the ruling of Allah is carried out against him. I have heard the Messenger of Allah (peace and blessings be upon him) say: So they carried out the killing immediately. This is a report from a single narrator regarding the one who changes his religion, so kill him. Mu'adh heard it from the Messenger of Allah and conveyed it to Abu Musa and the group who were with him, and they carried it out immediately. Is the argument established by a report from a single narrator? The argument is established. Now we come to the philosophy mentioned earlier. The philosophers and innovators say that we hold that a report from a single narrator is an argument in rulings, but not in creed. Now, do you think that Abu Musa, Mu'adh, Ali, and the other messengers sent by our Messenger (may Allah's prayers and peace be upon him), when they came to a tribe or a king, the first thing they called them to was prayer, purity, and ablution, and not creed? Creed, without a doubt. This is what was explicitly stated in the hadith of Mu'adh ibn Jabal when the Messenger (peace and blessings be upon him) sent him to Yemen. He said to him: And so the Messenger (peace and blessings be upon him) proceeded in explaining the rulings, and in ordering Mu'adh to proceed in that manner. He ordered him to start with what? With creed: the testimony that there is no god but Allah and that Muhammad is the Messenger of Allah. Here lies the great misguidance. So Mu'adh was an individual, and he called those people who knew nothing about Islam to creed, the foundation of all creeds, which is tawhid (the oneness of Allah). Was the argument established by this? Muslims believe the argument was established. But the philosophers who were influenced by some brilliant opinions contrary to the Book and the Sunnah say that a report from a single narrator does not establish an argument in creed. This means one of two things: either the Messenger of Allah (peace and blessings be upon him) was mistaken when he sent Mu'adh and others to call people to Islam, and this is disbelief (kufr). If a person says this, he has committed disbelief and exited the religion. And the only remaining option is that those who say a report from a single narrator is not an argument in creed are the misguided.