And from him, from Ibn Abi Umayr, from Jamil ibn Darraj, 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.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 4, p. 291