Lev 19:28 prohibits tattooing, but no reason for the prohibition is given. Since it appears in a context of pagan mourning practices (Lev 19:27,28) it is assumed that the reason for the prohibition lay in its association with such mourning practices. In this paper we explore the broader context of the law in biblical times, and how it was understood in subsequent rabbinic times. We propose that in the biblical period the prohibition was associated with the marking of slaves, and that in the subsequent rabbinic period it was associated with paganism.
So e.g.BDB p. 507. Others translate with the semantically close “on his hand” apparently construing yādô as an adverbial accusative; so HALOT p. 504a DCH vol. 4 p. 473b and most modern commentaries. Another possibility accepted by some commentators is that a haplography has occurred for yiktōb bǝ-yādô thus “Another will write with his hand ‘of the Lord’ ” (so e.g. Radak and ibn Ezra; the Septuagint also takes it as “and another shall write with his hand”; see DCH vol. 4 p. 473a). But since one would normally write “with the hand” the phrase bǝ-yādô is unnecessary and so this interpretation seems less plausible. We wish to thank Jo Ann Hackett for her insights on the meaning of this phrase. We might also note that the original meaning of the root k-t-b was probably “to puncture sew (as with an awl)” as for example in classical Arabic where kataba means both “to write” a meaning borrowed from Aramaic and “to sew (with an awl).” That meaning obviously fits with the notion of tattooing where the skin must be punctured to “write” the mark.