Deuteronomy 21:12

Overview - Deuteronomy 21
The expiation of an uncertain murder.
10 The usage of a captive taken to wife.
15 The first-born is not to be disinherited upon private affection.
18 A rebellious son is to be stoned to death.
22 The malefactor must not hang all night on a tree.
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Deuteronomy 21:12  (King James Version)
Then thou shalt bring her home to thine house; and she shall shave her head, and pare her nails;

and she shall
This was in token of renouncing her religion, and becoming a proselyte to that of the Jews. This is still a custom in the East: when a Christian turns Mohammedan, his head is shaved, and he is carried through the city, crying, {la eelah eela allah wemochammed resoolu 'llahee,} "There is no God but the God, and Mohammed is the prophet of God."
1 Corinthians 11:6 ; Ephesians 4:22

pare her nails
or, suffer to grow. Hebrew make, or dress.
{Wsethah eth tzipparneyha,} "and she shall make her nails;" i
e., probably neither paring nor letting them grow, but dressing or beautifying them as the Eastern women still do by tinging them with the leaves of an odoriferous plant called {alhenna,} which Hasselquist (p. 246) informs us, "grows in
India and in upper and lower Egypt, flowering from May to August. The leaves are pulverized and made into a paste with water: they bind this paste on the nails of their hands and feet, and keep it on all night. This gives them a deep yellow, which is greatly admired by Eastern nations. The colour lasts for three or four weeks before there is occasion to renew it. The custom is so ancient in Egypt, that I have seen the nails of mummies dyed in this manner."