Refraining from using solitary hadith as proof in creed is a newly-invented innovation:

In short, the proofs of the Qur’an and the Sunnah, together with the practice of the Companions and the statements of the scholars, furnish conclusive evidence—as we have explained—that one must accept the solitary report in every branch of the Sharīʿah, whether doctrinal or practical. Any attempt to differentiate between the two is an innovation unknown to the early generations. For this reason al-ʿAllāmah Ibn al-Qayyim, may Allah have mercy on him, said (3/412):

“This distinction is null by unanimous agreement of the ummah, for it has always taken these hadiths as evidence in informative, knowledge-based matters—meaning creed—just as it relies on them in prescriptive, practical matters. Indeed, the practical rulings themselves contain information about Allah: that He has legislated such-and-such, made it obligatory, and approved it as religion; and His legislation and religion ultimately trace back to His names and attributes. The Companions, their Followers, the generation after them, and the people of hadith and sunnah have consistently cited these reports in the issues of attributes, predestination, the divine names, and legal rulings. Never has it been transmitted from any of them that he permitted citing solitary reports for legal matters while forbidding them in reporting about Allah, His names, and His attributes. Where, then, are the predecessors of those who now separate the two fields? Their only forebears are a handful of late-coming theologians who have little concern for what has come from Allah, His Messenger, and His Companions. They divert hearts from seeking guidance in this regard through the Book, the Sunnah, and the words of the Companions, and instead refer people to the opinions of the scholastic theologians and the contrived principles of dialecticians. These are the ones known for drawing that distinction … They even claimed a consensus for it, yet the consensus they allege cannot be traced to any Imām of the Muslims, nor to a single Companion.”