Chapter on Ruling of the Traveller and the Sick Person Regarding Fasting

And from him, from al-Nadr, from Asim ibn Humayd, from Abu Basir, who said: I (narrator) said to Abu Abdillah عليه السلام, peace be upon him: “At what distance does a man shorten (the prayers)?” Imam عليه السلام said: “At the whiteness of a day, or two barids.” – meaning two postal stages (baridan) equal approximately 24 miles. Imam عليه السلام said: “For the Messenger of Allah سبحانه وتعالى, Allah’s سبحانه وتعالى blessings be upon him and his family, went out to Dhu Khushub and shortened (the prayers).” So I (narrator) asked: “How far is Dhu Khushub?” Imam عليه السلام said: “Two barids.”