Why was Cheshbon given by the Gadites?

Question

In Bamidbar 32:37 it says that Cheshbon was rebuilt by Reuven - seemingly, it was given to them after they reached the agreement with Moshe on the settlement of the land. In Yehoshua 13:17 it says that indeed, Cheshbon was part of Reuven's territory. However, in Yehoshua 21:37 and Divrei Hayamim 1:6:66 it says that Cheshbon was one of the cities given to the Levites by Gad. How can this be?

Answer 1

Your question is asked in the Sifsei Chachomim on Devarim 33:21. The pasuk over there writes as follows:

וַיַּ֤רְא רֵאשִׁית֙ ל֔וֹ כִּי־שָׁ֛ם חֶלְקַ֥ת מְחֹקֵ֖ק סָפ֑וּן וַיֵּתֵא֙ רָ֣אשֵׁי עָ֔ם צִדְקַ֤ת יְהֹוָה֙ עָשָׂ֔ה וּמִשְׁפָּטָ֖יו עִם־יִשְׂרָאֵֽל׃ {ס}        

He chose for himself the best, For there is the portion of the revered chieftain, Where the heads of the people come. He executed the LORD’s judgments And His decisions for Israel.

The Sifsei Chachomim notes:

אותה חלקה ספונה וטמונה כו'. הוצרך לזה, שלא נאמר שהמחוקק טמון רק מקום קבורתו, כלומר אותה חלקה שהוא קבור בה, כדכתיב (להלן לד ו) ולא ידע איש את קבורתו. יש מקשין, והאיך אפשר לומר שקבורת משה היא בנחלת בני גד, והלא קבורת משה היא בהר נבו, כמו שכתוב לקמן ויעל משה מערבות מואב אל הר נבו וגו', והר נבו היה בנחלת בני ראובן, כמו שכתוב בפרשת מטות (במדבר לב לז-לח) ובני ראובן בנו את חשבון וגו' ואת נבו וגו'. ונ"ל דמישור של נבו היה גדול, והעיר היתה עומדת במישור, וההר היה בחלקו של גד. ומפני שמתחלה היו ההר והעיר של אדם אחד, נקרא ההר על שם העיר, וגם לא היה רחוק כ"כ מן העיר, והיה עומד במישור של עיר, משום הכי נקרא ההר על שם העיר. וק"ל:

That plot is concealed, hidden, etc. Rashi says this so that one should not say that the great scribe is hidden, but rather the place of his burial, i.e., the plot he is buried in, as it is written (below 34:6), No man knows his burial place. There are those who question, how is it possible to say that Moshe’s burial place is in Gad’s inheritance? Was not his burial at Mount Nevo, as it is written below (34:1), Moshe went up from the plains of Moav to Mount Nevo etc. and Mount Nevo was in the inheritance of Reuvein as it is written in parshas Matos (Bamidbar 32:37-38), The tribe of Reuvein built up Cheshbon, etc. [and] Nevo, etc. It seems to me that the plain of Nevo was large and the town was established in the plain, while the mountain was in the portion of Gad. And because the mountain and town originally belonged to one person, the mountain was called by the town’s name. Also, it was not all that far from the town and it was situated in the plain of the town. Therefore the mountain was named after the town. (Sefaria translation)

So in conclusion, the region was seemingly quite large and whilst the actual town belonged to Reuven, the mountain was in the portion of Gad but retained the name of the town as it was originally owned by one person, or alternatively, it was not that far from the town so likewise kept the name.

This point is reiterated by the Chizkuni and makes specific reference to the pasuk in Bamidbar 32:37 also:

The name in this verse appears to relate to the summit of that range of mountains which was situated on the territory of Reuven, as pointed out in Numbers 32,37 where the members of the tribe of Reuven are described as having built Nebo, etc.; when it is written concerning the territory of the tribe of Gad: “for that is where the grave of the lawgiver is situated,” (Deut. 33,21) it appears that this must have been at the boundary between the territories of Reuven and Gad.