Ahmad ibn Hanbal was a prominent Islamic scholar and theologian born in 780 CE in Baghdad. He is best known as the founder of the Hanbali school of thought, one of the four major Sunni schools of Islamic jurisprudence. His teachings emphasized strict adherence to the Qur'an and Hadith, advocating for a return to the original sources of Islam. Ibn Hanbal faced significant challenges during his life, particularly during the Mihna, a period of religious persecution. Despite this, he remained steadfast in his beliefs and gained a large following. His works, especially the Musnad, a collection of hadith, continue to influence Islamic thought and practice today.