In his
commentary on Deut 17:17, Rashi argued that the command for kings not to
multiply wives is a reference to exponential
increase, and, further, is not a biblical condemnation of plural marriage:
NEITHER SHALL HE MULTIPLY WIVES TO HIMSELF —
only eighteen, for we find that David had six wives, and it was announced to
him (by Nathan the prophet): “[Thus saith the Lord . . . I gave thy master’s
wives into thy bosom] . . . and if that had been too little, I would add unto
thee such and such as these (i.e. twice as many)” (Sanh. 21a; Siphre). (Torah with Targum Onkelos and Rashi’s
Commentary, Volume 5: The Book of Devarim-Deuteronomy [ed. Rabbi A.M.
Silbermann; BN Publishing, 2014], 91)
On Rashi’s
commentary on Deut 17:16 (a similar command for a king not to multiply the
number of horses he owns), Rabbi A.M. Silbermann noted:
Rashi points out that לא ירבה לו סוסים and ולא ישיב העם מצרימה וכו are not two separate commandments. They form one command that
forbs the king to possess a large number of horses and at the same time states
why this is prohibited,--so that he may not send the people back to Egypt to purchase
horses. The same phraseology occurs in the next verse: Neither shall he multiply wives unto himself, so that his heart turn not away from God. (Ibid.,
210)
In other
words, Deut 17:17, in part, is a warning not to do what Solomon et al would do—be
led away by plural wives from pagan peoples.
One is
reminded of Jacob’s use of Deut 17:17 in Jacob 2 as a screed against David and
Solomon having “many” wives and concubines (i.e., an exponential increase of
plural wives that were not authorised by the Lord). For more, see:
Polygamy, Deuteronomy 17:17, and Jacob 2:24