Verses with the word manslayer in the Old Testament (2 verses):

Numbers 35:6
And among the cities which ye shall give unto the Levites there shall be six cities for refuge, which ye shall appoint for the manslayer, that he may flee thither: and to them ye shall add forty and two cities.

Numbers 35:12
And they shall be unto you cities for refuge from the avenger; that the manslayer die not, until he stand before the congregation in judgment.