Abu Ishaq said: Al-Harith left his will that Abdullah ibn Yazid should offer his funeral prayer; so he prayed over him. He then put him in the grave from the side of his legs and said: This is a Sunnah (model practice of the Prophet).
Related hadith on this topic
Explanation & Benefits
Shaykh Umar Farooq Saeedi
Benefits and Issues:
When a Companion refers to an action as Sunnah, what is meant is the Sunnah of the Messenger of Allah (sallallahu alayhi wa sallam), and this is technically termed as "Marfu' Hukmi" (attributed in ruling to the Prophet).
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 3211
Shaykh Safi ur-Rahman Mubarakpuri
Lexical Explanation:
«مَنْ قِبَلِ رَجْلَيِ الْقَبْرِ» ] That is, from the side where the feet of the deceased are. Here, the application of the word "state" is to the place, meaning that the word "state" is used but the place is intended.
Benefit:
From this, it is understood that the deceased should be lowered into the grave from the side of the feet. This was the practice among the people of Hijaz, and this is what Imam Shafi'i rahimahullah and Imam Ahmad rahimahullah have chosen, and this is superior, because no authentic narration proving the contrary has been established.
Narrators of the Hadith:
[حضرت ابواسحاق رحمہ الله ] Amr ibn Abdullah Sabi'i Hamdani Kufi was a well-known Tabi'i. Numerous narrations are reported from him, but he used to practice tadlis (concealing the source of a narration). In the latter part of his life, his mental balance deteriorated. He was born two years before the end of the caliphate of Uthman radi Allahu anhu. He passed away in 129 Hijri.
[حضرت عبداللہ بن یزید رضی اللہ عنہ ] Khatmi Ansari. He was from the tribe of Aws. When he was present at the Treaty of Hudaybiyyah, he was seventeen years old. In the battles of Jamal and Siffin, he was with Ali radi Allahu anhu. He came to Kufa. During the era of Ibn Zubair radi Allahu anhu, he was the governor of Kufa. He passed away in Kufa during that period.
Source: Bulugh al-Maram: Commentary by Safiur Rahman Mubarakpuri, Page: 465