The Messenger of Allah ﷺ forbade that one should travel to the land of the enemy taking the Qur'an with him.  

نَهَى رَسُولُ اللَّهِ ﷺ أَنْ يُسَافَرَ بِالْقُرْآنِ إِلَى أَرْضِ الْعَدُوِّ  

It has been narrated on the authority of Abdullah b. Umar that the Messenger of Allah ﷺ used to forbid that one should travel to the land of the enemy taking the Qur'an (with him) lest it should fall into the hands of the enemy.  

عَنْ رَسُولِ اللَّهِ ﷺ أَنَّهُ كَانَ يَنْهَى أَنْ يُسَافَرَ بِالْقُرْآنِ إِلَى أَرْضِ الْعَدُوِّ مَخَافَةَ أَنْ يَنَالَهُ الْعَدُوُّ  

Do not take the Qur'an on a journey with you, for I am afraid lost it should fall into the hands of the enemy. Ayyub (one of the narrators in the chain of transmitters) said: The enemy may seize it and may quarrel with you over it.  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ تُسَافِرُوا بِالْقُرْآنِ فَإِنِّي لاَ آمَنُ أَنْ يَنَالَهُ الْعَدُوُّ قَالَ أَيُّوبُ فَقَدْ نَالَهُ الْعَدُوُّ وَخَاصَمُوكُمْ بِهِ  

The above hadith has been narrated through several other chains with slight differences of wording.  

عَنِ النَّبِيِّ ﷺ فِي حَدِيثِ ابْنِ عُلَيَّةَ وَالثَّقَفِيِّ فَإِنِّي أَخَافُ وَفِي حَدِيثِ سُفْيَانَ وَحَدِيثِ الضَّحَّاكِ بْنِ عُثْمَانَ مَخَافَةَ أَنْ يَنَالَهُ الْعَدُوُّ