(Devarim 19:5) "and his hand swing the axe": From here it is ruled that if he intended to chop down a tree and it fell on a man and killed him, he is exiled.
"and the blade slip from the wood": from the haft (of the axe). Rebbi says: from the wood that was being chopped.
"and it find his neighbor and he die": to exclude his presenting himself. From here R. Eliezer b. Yaakov ruled: If, after the stone left his hand, the other put out his head and was hit by it, the first is not liable.
"he shall flee to one of these cities": He may not exile himself from one city to another.
(Ibid. 6) "Lest the redeemer of blood pursue the slayer": It is a mitzvah for him to pursue him.
"not having hated him": If he had hated him, he is not exiled.
"mitmol shilshom": As R. Yehudah says: "tmol": two days; "shilshom": three days (see #181).
(Ibid. 7) "Therefore, I command you, saying": Beth-din is being exhorted to this end.