As they were proceeding on their journey someone said to him, "I will follow you wherever you go." Jesus answered him, "Foxes have dens and birds of the sky have nests, but the Son of Man has nowhere to rest his head." And to another he said, "Follow me." But he replied, "(Lord,) let me go first and bury my father." But he answered him, "Let the dead bury their dead. But you, go and proclaim the kingdom of God." And another said, "I will follow you, Lord, but first let me say farewell to my family at home." (To him) Jesus said, "No one who sets a hand to the plow and looks to what was left behind is fit for the kingdom of God." (Lk 9:57-62)
Following Jesus does not take one to a home. Because foxes have dens and birds of the air have their nests to rest. Jesus’ journey does not lead him to a home and in fact he does not have one. He has set his foot towards Jerusalem and there is no rest for him in Jerusalem. He goes there to be hanged on the cross. And that was not the place of rest. Anyone who wants to be a follower should not seek for a secure place of rest.
Second follower (would have been a follower) wanted to go and fulfill his duty towards his father and then come back to follow him. There was no time to wait for one to complete his duties. Following Jesus is imminent and there was no time delay for that. If one wants to complete all his duties (however right and just they may be) to follow Jesus then he could not be a follower.
Third follower wanted to keep up his relationship. He wanted to give time and space for them. He wanted to greet them and then he wanted to follow Jesus. Jesus said there was time even to turn back. The journey that Jesus is making has not time frame (to bury the father)and no space frame (home) and no relations to greet (person). Kingdom is so important one should be ready to sacrifice all these: space, time and relationship.