Shams al-A’immah Muhammad bin Ahmad, was from Sarkhs. He passed away in 482 Hijr. Thus, he is a relatively early Imam of the Madhab.
He is one of the great authorities in the Madhab and authored authoritative works that were heavily relied upon by those who came after him. His best-known work is al-Mabsut. However, his Sharh al-Siyar al-Kabir is also of great significance.