Who was the first to compile the Hadith of the Messenger of Allah, may Allah's prayers and peace be upon him?

The Sunnah (definition) was not compiled during the time of the Prophet, peace be upon him, like the Qur'an. Rather, it was preserved in memories and transmitted orally, although some companions, like Abdullah ibn Amr, had written scrolls. Umar ibn al-Khattab considered compiling it but then changed his mind. The first to order its collection was Umar ibn Abd al-Aziz, who requested Abu Bakr ibn Hazm to write down whatever traditions of the Messenger of Allah, peace be upon him, existed, fearing the loss of knowledge. Al-Zuhri, who was a contemporary of Umar ibn Abd al-Aziz, recorded everything he heard of Hadith (definition) and sayings of the companions without categorization, thus laying the foundation for the compilation of the Sunnah. Then, compilation became widespread in the generation that followed, and it was collected in different cities. Subsequently, in the third century, Musnads were compiled, such as Musnad Imam Ahmad, followed by the Sahih (definition) collections like Bukhari and Muslim, and then the Sunan collections like Sunan Abi Dawud, Al-Nasa'i, Ibn Majah, and Al-Tirmidhi.