Prayer During Travel
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 59
وَ قَدْ رُوِيَ عَنِ اَلصَّادِقِ عَلَيْهِ اَلسَّلاَمُ أَنَّهُ قَالَ: «إِذَا خَرَجْتَ مِنْ مَنْزِلِكَ فَقَصِّرْ إِلَى أَنْ تَعُودَ إِلَيْهِ.
It has been narrated from Imam Jafar ibn Muhammad Al-Sadiq عليه السلام that He said: "When you leave your home, shorten your prayers until you return to it."
- Ṣaḥīḥ al-Faqīh