What is the evidentiary status of the practice of lowering the deceased lengthwise versus lowering transversely from the Qibla side?

Primary text

The evidence for lowering lengthwise is established by the narration Imam Ahmad reported on the authority of Abdullah bin Yazid al-Ansari, stating that Al-Harith commanded to be handled thus at his death, and the person lowered him into the grave from the foot end, stating, 'This is the Sunnah.' This implies the Sunnah of the Prophet (peace be upon him). Narrations from Ibn Umar and Ibn Abbas also state that the Prophet (peace be upon him) was lowered lengthwise from his head. The report attributed to Al-Nakha'i regarding the people of Medina's practice is deemed invalid because his own madhhab contradicts it, and because a visible, established Sunnah in burial cannot be changed by a large number of people without a clear cause or compelling authority.