Or HaChaim on Exodus 21:14/אור החיים על שמות כ״א:י״ד

1 וכי יזיד איש.. להרגו בערמה, If someone plans devious murder, etc. Mechilta concentrates on the word למות at the end of the verse and understands it as excluding "bringing him to trial, inflicting corporal punishment, or exile." This is the reason that Yoav (David's general) who had taken refuge in the Temple holding on to the altar was dragged away and executed. While it is true that Yoav was executed, this was because he was rebellious and not because he had murdered Avner or Amassa (compare Sanhedrin 49). He had fled before he could be brought to trial. The Talmud in Makkot 12 claims that Yoav's error in thinking that the altar could save his life was that at that time the altar was still a temporary structure, Solomon's Temple not having been built yet.

2I have noted that Maimonides writes in chapter 5,12-14 of his Hilchot Rotzeach that the altar serves as a refuge for unintentional killers as far as protection against an avenger who is a member of the victim's family is concerned. It does not act as an alternative to such a killer having to go into exile. Clearly, Maimonides had not seen the Baraitha which we quoted above according to which the word למות excludes exile, etc. The Baraitha's whole point is that if someone tries to save himself in the Holy Temple by holding on to the altar he can be dragged out only in order to be executed and not in order to be confined in a city of refuge. While it is true that one could offer a forced explanation that the words in the Baraitha ולא לגלות mean that that if someone is guilty of confinement in the city of refuge the family's avenger has no right to kill such a person, this is extremely forced seeing it contains no new element. We know this already. Besides, the words in the Baraitha which appear immediately before this comment about לא לגלות contradict such an explanation. The Baraitha had said: "not to have corporal punishment administered to him nor to be brought to trial." I have an even greater difficulty with the words of the author of Mishneh Lamelech who wonders why Maimonides makes a distinction between intentional and unintentional killers seeking refuge at the altar, whereas he makes no such difference at all. The latter statement is incomprehensible even if we did not have a Baraitha at all. We have no authority to rule that the altar fails to act as refuge except in a situation specifically excluded by the Torah.