Some expressions in Scripture aren't clear right away. For example, Deuteronomy 21:12 makes reference to the paring of nails. The Dake Annotated Reference Bible offers the following explanatory note on page 216 of the Old Testament:
The Heb. for "pare her nails" is asah, to make, not to cut or leave uncut. It refers to changing by a personal act, and may mean changing the color with hennah, a plant which grows in India and Egypt and flowers between May and August. The leaves were made into powder and mixed with water to form a paste. Women would leave this on their nails overnight to turn them a reddish yellow. The color would last a month before another application was needed. Many women stained the palms of their hands and the soles of their feet in the same way. Perhaps it was this custom referred to in 2 Sam. 19:24 where Mephibosheth had not dressed his feet (made them colored).