The Torah in Parashat Shoftim (Debarim 17:18) commands that the Jewish king must write a Sefer Torah and keep it with him at all times, wherever he goes. The Sefer Ha’hinuch explains that a king is especially prone to sinning, because he enjoys absolute power, such that nobody criticizes him, instructs him, or corrects his behavior. Moreover, as he has complete authority over the people, to the point where he has the right to order a citizen’s execution, he can easily become arrogant, and consider himself above the law. Therefore, it is critically important for him to constantly review the laws and messages of the Torah, to be reminded of His subservience to G-d and His obligation to observe all the Torah’s laws. This is necessary for him to resist the Yeser Ha’ra (sinful inclination), remain humble, and submit to the Torah’s authority.
The king is obligated to keep the Torah with him at all times, except when he uses the restroom or when he bathes.
The king’s Torah scroll was copied from the “Sefer Ha’azara” – the original Sefer Torah written by Moshe Rabbenu. This scroll was kept in the Azara (courtyard of the Bet Ha’mikdash) and read by the king during the Hakhel ceremony, held every seven years. This was the most authentic copy of the Sefer Torah, as it was the original text written by Moshe himself, and this scroll was copied from when writing the king’s Sefer