but more relevantly for us it's in the Bible, in Exodus, Leviticus, and Deuteronomy.

hmm, coincidentally i was thinking the same thing when this thread came up, and wondering if the New Testament offers us any opinion (since things kinda change tone a bit somewhere in the chasm between Malachi and Matthew), and according to my reliable source (Hi, S!):

Hammurabi was a Babylonian legislator, whose code makes the Mosaic Law seem positively warm and fuzzy. The NT neither endorses nor condemns capital punishment, viewing such matters as affairs of secular government, not religious faith.

i offer this just in case anyone else besides me wondered.

btw, atomica's (admittedly lacking) etymological notes on 'mosaic' provide no biblical mention at all (other than, specifically, Mosaic Law). i fail to see a connection, as to meaning, but it seems unlikely that the derivation could have been entirely separate. i wonder what the OED has to say? hinthintjoe