Hadith 1794
Ibn 'Umar (May Allah be pleased with them) said:
عن ابن عمر رضي الله عنهما قال: "نهى رسول الله صلى الله عليه وسلم أن يسافر بالقرآن إلى أرض العدو" ((متفق عليه)).
The Messenger of Allah (ﷺ) forbade travelling to the land of the enemy carrying the Qur'an. [Al-Bukhari and Muslim].
In plain words
The Prophet forbade travelling into enemy territory while carrying the Qur'an. It reflects care to keep the sacred text from falling into hostile hands.
Reference : Riyad as-Salihin 1794 In-book reference : Book 17, Hadith 284