Numbers - Chapter 35

The Levites were not given areas of land - but they did have towns, spread throughout the country.  Six of these were to be "cities of refuge", to which a person who had killed someone could flee.  The person was safe within the city of refuge, but not if they left it.  However, they could safely leave the city after the death of the High Priest.

The link to Jesus is set out in Hebrews 6 - "we who have fled for refuge might have strong encouragement to hold fast to the hope set before us".  And we are all under sentence of death for our sins until after the death of our High Priest - Jesus.