The gifts of the twelve princes of the tribes were not only equal in number, but also in the size and width of the objects bestowed, every tribe making exactly the same offering to the sanctuary. None among them wished to outrival the others, but such harmony reigned among them and such unity of spirit that God valued the service of each as if he had brought not only his own gifts but also those of his companions. As a reward for this mutual regard and friendship, God granted them the distinction of permitting them to present their offerings even on the Sabbath day.
Shabbat Before the Altar
Legends of the Jews 3:107