As for what was narrated by Ahmad ibn Muhammad from Ibn Abi Nasr from Abu al-Hasan al-Ridha عليه السلام, peace be upon him, he said: I asked Imam al-Ridha عليه السلام about a man who intends to travel, at what distance does he shorten (the prayer)? Imam عليه السلام said: “At three ‘barid’ (‘burud’).”