daf bit: Bava Metzia 61

The g'mara discusses the injunction "you shall not steal", and then Rav Yemar said to Rav Ashi: for what purpose does the torah then prohibit false weights? He replied: to forbid soaking them in salt. But this is pure robbery! He replied: to teach that one transgresses at the very moment that this is done. (61b)

(That is, using the false weights would violate "you shall not steal", but even having them is a prohibition all to itself.)