...six covered wagons and twelve oxen, [one wagon and two oxen] for two Nesi'im [each]...
(Bamidbar 7:3)
Q: On the surface, it's hard to understand why two Nesi'im together brought merely one wagon. After all, when the Jews donated to the Mishkan, they gave so much that Moshe had to tell them to stop giving due to the surplus. So, why were the Nesi'im so 'economical' with their donations?
A: The Lubavitcher Rebbe explains that carrying the Mishkan was a task Divinely given to the Levi'im, as seen in Parashat Bamidbar (4:24) that they were appointed to 'perform service and carry (the parts of the Mishkan)', so the Nesi'im were concerned that if they gave too much wagons, making the transport of the parts of the Mishkan very easy, they would be taking away the privilege of carrying it. So, they donated just six wagons, which were enough to support the parts of the Mishkan with difficulty (as we learn in Shabbat 99a, that the wagons were loaded to the max and that they were the absolute minimum size possible). In this way, the Nesi'im intended to take away some of the immense burden of transporting the parts of the Mishkan, but without taking away what was Divinely alloted to the Levi'im.
