Riyad Us-Saliheen (Gardens of the Righteous)

Chapter 363
Prohibition of Carrying the Qur'an into the Land of Enemy

1794. Ibn `Umar (May Allah be pleased with them) said: The Messenger of Allah (PBUH) forbade travelling to the land of the enemy carrying the Qur'an.
[Al-Bukhari and Muslim].

Commentary:  This prohibition is out of fear that the disbelievers might abase and demean the Qur'an and will not give it due respect. It is, however, permissible to take it to places where there is no such fear.