仁王般若經疏 1.21

1.21

耆闍崛山中者，王舍城有六精舍：一竹園精舍，在平地，迦園陀長者之所造，去城西北三十里；二少力獨上山精舍；三七葉穴山精舍；四四天王穴山精舍；五蛇穴精舍；六祇闍崛山精舍，此翻鷲頭山，耆闍名鷲，崛名頭，此山頂似鷲，王舍城人見其似鷲故因傳名鷲頭山。又王舍城南多諸尸陀林，鳥獸來食，多集諸鷲鳥，故云鷲頭山也。五山者，東方象頭、南方馬頭、西方羊頭、北方師子頭、中央鷲頭也。

As for "on Mount Gṛdhrakūṭa": in Rājagṛha there are six monasteries: first, the Bamboo Grove Monastery, on flat ground, built by the elder Kalandaka, thirty li northwest of the city; second, the Small-Strength Sole-Ascent Mountain Monastery; third, the Saptaparṇa Cave Mountain Monastery; fourth, the Cave Mountain Monastery of the Four Heavenly Kings; fifth, the Serpent Cave Monastery; sixth, the Gṛdhrakūṭa Mountain Monastery, translated here as Vulture Peak Mountain—gṛdhra means vulture, kūṭa means peak; this mountain summit resembles a vulture, and the people of Rājagṛha, seeing that it resembled a vulture, consequently handed down the name Vulture Peak Mountain. Furthermore, south of Rājagṛha there are many śmaśānas (charnel grounds) where birds and beasts come to feed, and many vultures gather there; hence it is called Vulture Peak Mountain. The five mountains are: Elephant Head in the east, Horse Head in the south, Sheep Head in the west, Lion Head in the north, and Vulture Peak in the center.