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

As for what Muhammad ibn Yaqub narrated from Ali ibn Ibrahim, from his father, from Ibn Abi Umayr, from Jamil, from Zurarah, from Abu Ja’far عليه السلام, peace be upon him, who said: Imam عليه السلام said: “Shortening (the prayer) is in one barid, and one barid is four farsakhs.”