法苑珠林 12.9

12.9

又中阿含經云。如來爾時將詣雙樹。四襞欝多羅僧以為施座。僧伽梨為枕右脇而臥。足足相累而故涅槃。

Furthermore, the Madhyama-āgama says: The Tathāgata was then about to proceed to the twin trees. He folded his uttarāsaṅga four times to make a seat, took his saṅghāṭī as a pillow, and lay on his right side, with one foot resting upon the other, and thus entered nirvāṇa.