Numbers 35:10

7 Forty-eight towns are to be given to the Levites, all with land round them.

8 And these towns are to be given out of the heritage of the children of Israel, taking the greater number from those who have much, and a smaller number from those who have little: everyone, in the measure of his heritage, is to give of his property to the Levites.

9 And the Lord said to Moses,

10 Say to the children of Israel, when you have gone over Jordan into the land of Canaan;

11 Then let certain towns be marked out as safe places to which anyone who takes the life of another in error may go in flight.

12 In these towns you may be safe from him who has the right of punishment; so that death may not overtake the taker of life till he has been judged by the meeting of the people.

13 Six of the towns which you give will be such safe places;