Parshat Matot-Massei

He that kills a person accidentally... shall remain [exiled in the "city of refuge"] until the death of the High Priest (Numbers 35:11, 25)

The mothers of high priests would provide food and clothing for the exiled killers, that they should not pray for their son's death.

Why is the High Priest to blame? --As they say here [in Babylon], "Toby did the jobbing and Ziggad got the slogging?" or as they say there [in the Land of Israel]: "Shechem got him a wife and Mabgai caught the knife?" Said a venerable old scholar: I heard an explanation at one of the seasonal lectures of Raba, that he failed to pray for his generation.

As was the case of that fellow who was devoured by a lion some three parasangs from Rabbi Joshua ben Levi's town, and Elijah the Prophet refused to visit Rabbi Joshua on that account for three days.

(Talmud, Makot 11a)