Al-Kāfi - The Book of Food

ِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنْ أَحْ٠َّدِ بْنِ أَبِي نَصْرٍ عَنِ الرِّضَا ( عليه السلا٠) قَالَ إِذَا أَكَلْتَ شَيْئاً فَاسْتَلْقِ عَلَى قَفَاكَ وَ ضَعْ رِجْلَكَ الْيُ٠ْنَى عَلَى الْيُسْرَى. 21.

A number of our people have narrated from Sahl ibn Ziyad from Ahmad ibn Muhammad from ibn abu Nasr who has said the following: “Abu al-Hassan, al-Rida’ (a.s.), has said, ‘When you eat [something], then lie down on your back, then place your right leg on your left leg.’” شهور - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (22/116))