The Four Schools of Jurisprudence and Their Validity

Question: The four schools of jurisprudence: the Hanbali, Shafi'i, Maliki, and Hanafi schools. Are they valid? And in which era did they emerge?

Answer: These four schools of jurisprudence are well-known schools that spread in the second century and thereafter.
As for the school of Abu Hanifah, it became known and spread in the second century, and likewise the school of Malik in the second century. As for the schools of Imam al-Shafi'i and Ahmad, their schools spread in the third century. All of them are upon good and guidance, and their goal is to seek the truth indicated by the Book of Allah and the Sunnah of His Messenger (peace and blessings be upon him). However, this does not mean that each one of them is infallible and that no error occurs from them; rather, each one of them has errors according to what reached them of the Sunnah, and according to what they knew of the Book of Allah .
Some of them may miss some knowledge from the Book of Allah and the Sunnah of the Messenger of Allah (peace and blessings be upon him), and they issue rulings based on what they know. This is a known matter among the people of knowledge.
Others from the people of knowledge are associated with these four, such as al-Awza'i, Ishaq ibn Rahawayh, Sufyan al-Thawri, Sufyan ibn Uyaynah, Waki' ibn al-Jarrah, and other well-known imams. Each one of them exercises independent legal reasoning in the knowledge that reaches him. So whoever is correct has two rewards, and whoever is wrong has the reward of his independent legal reasoning, and he misses the reward of correctness, as the Sunnah from the Prophet (peace and blessings be upon him) has confirmed this. And Allah is the One who grants success.