What is the liability of two witnesses who testify to a conditional manumission that is later revoked?

Primary text

If two witnesses testify that a master manumitted a slave conditional upon a guarantee of one hundred dirhams, and the slave's actual value is two hundred, and the judge rules based on this testimony, the master is entitled to recover one hundred dirhams from the witnesses upon the retraction of their testimony. This is because the one hundred dirhams represents the confirmed portion of the slave's value or the guaranteed loss.