Abu Abdallah Ahmad ibn Muhammad al-Jayhani was a vizier of the Samanid dynasty from 975/6 to 977.
He was a member of the Jayhani family, that provided several officials to the Samanids.
As the sources generally refer to these individuals only by their kunya and nisbah, separating the lives and identities of the family members is difficult.
[1] Abu Abdallah himself was appointed as vizier by Mansur I in 975/6, and remained in office under Nuh II until November/December 977, when he asked to be relieved on account of his advanced age.
[1][2] Like his father, Abu Ahmad is said to have been a convert (or at least sympathetic) to Isma'ilism.