Albert Barnes on Luke 13:33

I must walk, &c. I must remain here this short time. These three days I must do cures here, and then I shall depart, though not for fear of Herod. It will be because my time will have come, and I shall go up to Jerusalem to die.

For it cannot be that a prophet should perish out of Jerusalem. I have no fear that Herod will put me to death in Galilee. I shall not depart on that account. Jerusalem is the place where the prophets die, and where I am to die. I am not at all alarmed, therefore, at any threats of Herod, for my life is safe until I arrive at Jerusalem. Go and tell him, therefore, that I fear him not. I shall work here as long as it is proper, and shall then go up to Jerusalem to die. The reason why he said that a prophet could not perish elsewhere than in Jerusalem might be--

1st. That he knew that he would be tried on a charge of blasphemy, and no other court could have cognizance of that crime but the great council or Sanhedrim, and so he was not afraid of any threats of Herod.

2nd. It had been the fact that the prophets had been chiefly slain there. The meaning is, "It cannot easily be done elsewhere; it is not usually done. Prophets have generally perished there, and there I am to die. I am safe, therefore, from the fear of Herod, and shall not take the advice given and leave his territory."