Midrash su Numeri 7:85

(Bamidbar 7:85) "One hundred and thirty (shekels was the weight of) each silver dish": Why is this written (again)? From "his offering was one silver dish, etc." I know only that the "bowl," where it is explicitly stated, was "in the shekel of the sanctuary." Whence do I derive the same for the "dish"? It is, therefore, written (Ibid.) "All the silver of the vessels — two thousand and four hundred shekels in the shekel of the sanctuary." And to teach that not as common vessels were the Temple vessels. Common vessels — If he weighs them one by one and then weighs them all together, there is some increase or decrease (in the resultant weight); but with these (Temple vessels), there is neither increase nor decrease. R. Nathan says: Temple vessels — if one weighed them and then melted them into a mold, and then re-made them into vessels, there would be no increase or decrease (in the resultant weight).