The imams (experts in Ahadith) and (critical) scholars of hadith sciences made great efforts in preserving the hadith. They collected the texts and chains (asnaad) and explained the conditions of the narrators in detail. They recorded for posterity not only the exact wording of the hadith but also took pains to elaborate on the differences of the narrators in the chains. https://vacuumdoctores.shop/product-category/sweeping-machinery-rider-and-walk-behind/