R. Akiva says: Whence is it derived that one should not keep a sela less than (the value of a shekel, or a dinar less than (the value of) a tarfik? From "There shall not be unto you." (Ibid. 14) "There shall not be unto you in your house a measure and a measure, great and small":
R. Yossi Berebbi says: If you have fulfilled (Ibid. 15) "A whole and just stone," then (Ibid.) "there shall be unto you" (i.e., you will prosper). And if you have transgressed (Ibid. 13) "A stone and a stone," then (Ibid.) "there shall not be unto you."