How did the teachings and sayings of the Prophet (peace be upon him) reach the people in the Prophetic era?

The sayings and teachings of the Prophet, peace and blessings be upon him, spread and reached people through the Companions who accompanied him and carried his knowledge and guidance. Then, they dispersed into various cities, spreading Hadith and teaching people their religion. This is evidenced by what Imam Malik said to the Abbasid Caliph when the latter wanted to distribute Al-Muwatta’ throughout the cities and compel people to act upon it. Imam Malik refused, explaining that the Companions had dispersed across different regions and narrated Hadiths other than those of the people of Hijaz, and that people adopted what reached them from their scholars.