Charles Ellicott Commentary Exodus 21:14

"And if a man come presumptuously upon his neighbor, to slay him with guile; thou shalt take him from mine altar, that he may die." — Exodus 21:14 (ASV)

If a man come presumptuously. —Rather, if a man comes maliciously, or with premeditation. (Vulgate, de industria.)

You shall take him from my altar. —Compare 1 Kings 2:28–34. In most parts of the ancient world, a scruple was felt about putting criminals to death once they had taken sanctuary, and those who did so were regarded as accursed (Herodotus 5:71, 72; Plutarch, Life of Solon, § 12). The Mosaic Law regarded this scruple as a superstition and refused to sanction it.