"And it shall be, when [the king] sits upon the throne of his kingdom, and he shall write for himself a copy of this Torah"—Deuteronomy 17:18.
A Jewish king is required to write (or acquire) for himself a Torah Scroll—from which he does not part all the days of his reign.
This scroll is in addition to the scroll he already wrote (or acquired) for himself before he ascended the throne (pursuant to Positive Commandment 18).
