It was narrated from Ibn ‘Umar that the Messenger of Allah ﷺ forbade traveling with the Qur’an to the land of the enemy, lest the enemy gets hold of it. (Using translation from Ibn Mājah 2879)
«نَهَى رَسُولُ اللَّهِ ﷺ أَنْ يُسَافَرَ بِالْقُرْآنِ إِلَى أَرْضِ الْعَدُوِّ مَخَافَةَ أَنْ يَنَالَهُ الْعَدُوُّ»