(88) باب فِي الْمُصْحَفِ يُسَافَرُ بِهِ إِلَى أَرْضِ الْعَدُوِّ
'Abd Allaah bin 'Umar said "The Apostle of Allaah(ﷺ) prohibited to travel with a copy of the Qur'an to the enemy territory. The narrator Malik said "(It is) I think lest the enemy should take it.
Reference: Sunan Abi Dawud 2610
In-book reference: Book 15, Hadith 134
English translation: Book 14, Hadith 2604