Sforno on Exodus 18:27/ספורנו על שמות י״ח:כ״ז

1וישלח משה את חותנו, for he did not want to join the fate of the Jewish people by going with them to the land of Canaan. He had said clearly: לא אלך, “I am not going, for I am going back to my own country to my birthplace.” (Numbers 10,30) Perhaps this was due to his being of advanced age; we encounter such reticence to move to a better place when David offered Barzilai a home in Jerusalem and he declined, citing that at his age he would not enjoy what Jerusalem had to offer anyway. (Samuel II 19,38) He preferred to be buried with his father and mother. Yitro’s sons (and daughters?) however definitely joined the Jewish people in their journey to the Holy Land, as we know from Judges 1,16 where they are described as the children of the Keyni, the father-in-law of Moses. Bileam also prophesied concerning their future in Numbers 24,21.