To al-Haarith al-Hamdani
Nahj al-Balāgha|Volume 1|Book 2|Chapter 69
وَلَا تُسَافِرْ فِي يَوْمِ جُمُعَةٍ حَتّى تَشْهَدَ الصَّلَاةَ إِلَّا فَاصِلًا فِي سَبِيلِ اللهِ، أَوْ فِي أَمْر تُعْذَرُ بِهِ.
Do not undertake a journey on Friday until you have attended the prayers, except when you are going in the way of Allāh, or in an excusable matter.