The Secret Entrance
When the tribe of Yosef set out to conquer the city of Beit El, formerly known as Luz, there was a serious problem in locating the perfectly concealed entrance to the fortified city. Some advance scouts observed a resident of the city who had exited the city and asked him to show them the entrance. A giant luz tree stood in front of a cave which served as the entrance and only the citys inhabitants were aware that the tree was hollow and could be traversed.
The scouts promised to reward this fellow with protection if he showed them the entrance. He pointed his finger toward the mysterious tree and thus enabled the Israelites to conquer the city. True to their promise they spared the informer and his family. He subsequently moved to the Hittite area of the land and established a city which he named Luz. The kindness the guide showed to the Israelites was rewarded by this new citys invulnerability to death. When its aged inhabitants grew weary of life they went outside the city walls to die.
This is cited by our Talmudic Sages as an example of the great reward for one who helps another in reaching his destination.