The capital of the believer is his religion, it is always with him, he does not leave it behind when on a journey and neither does he entrust it to another.

—Al-Ḥasan al-Baṣrī [d 110H/728CE]

(Read on pg 37, Ibn Rajab al-Hanbali and Abu Bakr al-Ajurri, The Journey of the Strangers. Daar as-Sunnah Publishers. Birmingham: 2009.)