("their remnants) bound up in their clothes on their shoulders": R. Nathan says: Were there no beasts there (to carry the remnants)? Is it not written (Ibid. 38) "And also a great multitude went up with them, and flocks and herds"? Why, then, "on their shoulders"? To betoken their love of the mitzvoth.
Their Remnants Bound Up in Their Clothes on Their
Mekhilta Tractate Pischa 13:30