# Please, may the king call to mind Yahweh your God

"Please promise in the name of Yahweh your God" 

# the avenger of blood

"the man who wants to avenge my son's brother's death" 

# destroy anyone further

"cause anyone else to die." This is in addition to the brother who already died.

# that they will not destroy my son

"that they will not kill my son" or "that they will not execute my son"

# As Yahweh lives

"I promise you, as surely as Yahweh lives" or "In Yahweh's name I promise"

# not one hair of your son will fall to the ground

"your son will be completely safe"