Hazrat Mukhtar bin Fulful says that I asked Hazrat Anas (may Allah be pleased with him) about the testimony of a slave, so he replied that it is valid.

Hazrat Shurayh considered the testimony of a slave to be valid.

Ibrahim says that the predecessors considered the testimony of a slave valid in minor matters.

Hazrat Ammar Dahni narrates that in front of me, in the court of Hazrat Shurayh, a slave gave testimony regarding a house, and he accepted his testimony as valid. Someone said, "But he is a slave." He replied, "We are all slaves, and our mother is Hawwa (Eve)."

Hazrat Sha'bi narrates that once Hazrat Shurayh said, "We do not consider the testimony of a slave to be valid." Hazrat Ali (may Allah be pleased with him) said, "We used to consider the testimony of a slave to be valid." After that, Hazrat Shurayh would accept the testimony of a slave in favor of everyone except his master.

21495 - He said: So Shurayh (afterwards) would permit it except (for his master).