Midrasch zu Bamidbar 10:32

(Exod. 18:5–6:) NOW JETHRO, MOSES' FATHER-IN-LAW CAME…. AND HE SAID UNTO MOSES: I AM YOUR FATHER-IN-LAW…. Who said to Moses: I AM YOUR FATHER-IN-LAW? He was unable to come to Moses. What did he do? He wrote a letter and tied it on an arrow. Then he shot, and the arrow came to Moses. Moses read it and went out to him, as stated (in vs. 7): SO MOSES WENT OUT TO MEET JETHRO. He entered the camp along with him. What is written (in vs. 12)? AND AARON CAME WITH ALL THE ELDERS OF ISRAEL TO EAT BREAD <BEFORE THE LORD WITH MOSES' FATHER-IN-LAW >. When they had eaten with him, he said: Give me permission to go to my <own> place. Moses said to him (in Numb. 10:32): IT SHALL BE THAT, IF YOU COME WITH US, IT SHALL COME TO PASS THAT WHATEVER GOOD THE LORD DOES FOR US WE WILL DO FOR YOU. <Jethro> said to him: I want to go and utter the Holy One's praise in my own place. Immediately (in Exod. 18:27): MOSES SENT HIS FATHER-IN-LAW AWAY…. Now when the Holy One does miracles for Israel, they praise him [and the nations of the world praise him]. Thus it is stated (in Ps. 138:4): {THESE PEOPLES} ALL THE KINGS OF THE EARTH SHALL GIVE THANKS TO YOU, [O LORD,] FOR THEY HAVE HEARD THE WORDS OF YOUR MOUTH.

(Bamidbar 10:32) "And it shall be, if you go with us, that good which the L-rd will accord to us, we shall accord to you." Now what good did they accord to him? They said: When Israel apportioned the land, they left to him the choicest land of Jericho, five hundred by five hundred cubits. Whoever would build the Temple, would take that land, and (in the interim) it was given (as a holding) to the sons of Yithro, as it is written (I Kings 6:1) "And it was in the four hundred and eighteenth year of the exodus of the children of Israel from the land of Egypt" (that the Temple was built). Deduct forty years for their journeying in the desert, and we find them (the sons of Yithro) to have eaten of that land for four hundred and forty years, and when the Shechinah reposed itself in the portion of Benjamin, the sons of Benjamin came to take their portion, and they (the sons of Yithro) vacated it for them.