Musannaf Ibn Abi Shayba 35:16

Ibn Numayr and Abu Usamah narrated to us, from Ubayd Allah ibn Umar, from Nafi, from Ibn Umar: That the Prophet, peace and blessings of Allah be upon him, forbade traveling with the Quran to the land of the enemy, for fear that the enemy might obtain it. And he mentioned that Abu Hanifah said: There is no harm in that.