Al-Kāfi

Hadith 742
burial
3ـ عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنِ الْحَسَنِ بْنِ مَحْبُوبٍ عَنِ الْعَلاَءِ بْنِ رَزِينٍ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ قَالَ سَأَلْتُ أَحَدَهُمَا (عَلَيْهِما الْسَّلام) عَنِ الْمَيِّتِ فَقَالَ تَسُلُّهُ مِنْ قِبَلِ الرِّجْلَيْنِ وَتُلْزِقُ الْقَبْرَ بِالأرْضِ إِلَى قَدْرِ أَرْبَعِ أَصَابِعَ مُفَرَّجَاتٍ وَتُرَبِّعُ قَبْرَهُ.
3. A number of our people have narrated from Sahl ibn Ziyad from al-Hassan ibn Mahbub from al-‘Ala’ ibn Razin from Muhammad ibn Muslim who has said the following: “I asked one of the two Imam, Alayhim al-Salam, about a deceased. He said, ‘Place him in the grave from the side of the feet. Keep the grave above the ground by four open fingers and make it four cornered.’”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī