Sa’ad from Abu Ja’far from his father, and Muhammad ibn Khalid al-Barqi from Abdillah ibn al-Mughira from Ishaq ibn Ammar from Abu Ibrahim (Imam al-Kadhim عليه السلام), peace be upon him, who said: I asked Imam al-Kadhim عليه السلام about the mule drivers who hire out animals, and said: “They are constantly traveling, whenever some opportunity comes to them, they set out.” Imam عليه السلام said: “They are required to shorten (the prayer) when they travel.”