Numbers 7:3

Six covered wagons. צָב can only mean “covered.” Similarly, “[They will bring your brothers from all the nations . . . with horses and chariots] וּבַצַּבִּים וּבַפְּרָדִים,” “in covered wagons and on mules . . .” Covered wagons are called צַבִּים . [Some interpret צָב in the sense of הַצְבִי יִשְׂרָאֵל, (“The finest in Israel.”) They (the wagons) were fine looking.]

They placed them before the Mishkon. Because Moshe did not accept [the gift] from their hands until [so] instructed by the omnipresent [God.] R’ Noson said, “Why did the leaders see fit to contribute here at the outset, but for the materials of the Mishkon, they did not contribute at the outset? Because the leaders said as follows: “Let the community contribute as they wish, and any shortfall, we will furnish.” But when they saw that the community had supplied everything, as it is said, “the material was sufficient,” they said, “Now what can we do”? They brought the onyx stones, and the stones set into the ephod and breastplate. This is why they contributed here at the outset.

and they brought their offering before the Lord; six wagons covered and fitted up, and twelve oxen; one wagon for two princes and one ox for each. But Mosheh was not willing to receive them, and they brought them before the tabernacle.

AND THEY BROUGHT THEIR OFFERING BEFORE THE ETERNAL. Since the wagons [which the princes brought] were for the purpose of the offerings [i.e., for transporting the Tabernacle, where offerings are made before G-d] they are also called “offering.” Similarly, And we have brought the Eternal’s offering, what every man hath gotten, of jewels of gold, meaning “an offering” for the repairs of the Tabernacle. Now the princes thought that it would be impossible for the Levites to carry on their shoulders the boards of the Tabernacle and the sockets, which were very heavy, and therefore they brought the wagons of their own accord, for such is the way that all those who carry houses of kings and their palatial tents adopt, transporting them on wagons.
We may also explain that the expression And they brought their offering before the Eternal, six wagons ‘tzov,’ means six large wagons bearing their offerings, and twelve oxen drawing the wagons. Thus they brought the wagons laden [with the offerings], and the oxen [drawing the wagons] before the Tabernacle. And G-d commanded Moses, Take all of it of them, and the wagons and the oxen which were not brought for offerings shall do the service of the Tent of Meeting. Afterwards the princes took their offerings down from the wagons and brought them before the Tabernacle, intending to offer them all up on that day since they had been given permission to offer them before Him, but G-d commanded, each prince on his day shall they bring their offerings. And because of this [i.e., since the wagons that the princes brought contained the animals that they intended to offer up] it was not necessary now that He should say to Moses “take it of them,” [as the original statement already implies G-d’s consent to the offerings as well]., the question arises: when the princes came back and brought the actual dedication-offerings, why did G-d likewise not tell Moses to take the offerings from them? Hence the second interpretation is to be preferred. And it is a linguistic expression [in the Sacred Language] to say “wagons” when referring to their contents, just like: those who eat ‘shulchan Izebel’ [literally: “Jezebel’s table,” which means “the food on Jezebel’s table”]. So also: for all ‘sha’ar ami’ do know [literally: for all “the gates of my people” do know, which means: “for all the people in the gates of my people do know”]. And [likewise we find] in …

עגלות, seeing that the word is in a construct mode, i.e. עגלות צב, the vowel pattern is “eglot,” “draught carts”, instead of “agalot,” “carts.” We know similar vowel pattern changes in the word “essrot,” “tens of,” instead of simply assarot, tens. When the Torah writes that “one” cart was brought by a team of two princes it uses the standard vowel pattern agalah, as in that part of the verse the princes are the adjective (so to speak) and not the carts, as in the beginning of the verse.

צב, the word has different meanings in different contexts. In Isaiah 66,20 בצבים ובפרדים, “with mules and dromedaries,” it clearly refers to a category of animal. In our context it means animals that are used to be traveling with an army, צבא. The animals in question are able to travel long distances.

עגלה על שני הנשיאים. The reason that they shared a cart each was not that they were stingy, but that they wanted to demonstrate that there was no rivalry between them, but that, on the contrary, they felt like brothers one toward the other. Such sentiments have been recorded in the Torah in Deuteronomy 33,5 ויהי בישורון מלך בהתאסף ראשי עם, יחד, “Moses was king in Yeshurun when all the people gathered together;” [a king is not someone aloof, in an ivory tower, but his distinction becomes relevant only in his being part of his people, יחד, together.” The opposite is reported in Hoseah 10,2 חלק לבם עתה יאשמו, “when its collective heart is divided, this is they their guilt.”