The meaning is: Since taking another person’s life by any means whatever is murder and exposes the murderer to the penalty of retaliation, if the d…

But if he thrust him suddenly ... — See Deuteronomy 19:4-5, where the meaning of the law is illustrated.

But if he thrust him suddenly, without enmity
Push him from a precipice, before he is aware, without any malicious d…

To show plainly the abhorrence of murder, and to provide more effectively for the punishment of the murderer, the nearest relation of the deceased,…