The words vayihad Yitro (Exodus 18:9), generally translated "and Jethro rejoiced," are interpreted by the Talmudists as "he circumcised himself"; or "he felt a stinging in his flesh"; that is to say, he was sorry for the loss of the Egyptians, his former coreligionists.
The words vayihad Yitro (Exodus 18:9), typically translated as 'and Jethro rejoiced,' are reinterpreted by the Talmudists to mean 'he underwent circumcision' or 'he felt a painful sensation in his body'; essentially, he was regretful for the loss of the Egyptians, his former co-religionists.