釋氏要覽 1.23

1.23

即甘蔗王擯出四太子。一名炬面。二名金色。三名象眾。四名尼拘羅（隋言別成）四子初至雪山北。頓駕大樹枝條蓊欝之下。是故名奢夷耆耶。今言舍夷必。梵語訛略也。五分律云。近雪山北舍夷林。築城營舍。又缾沙王始問佛生何國。佛言生舍夷國（今詳。必因樹命國。從國稱氏）○法苑云。舍夷者。西方之貴姓也。

Namely, King Sugarcane banished his four princes: the first was named Torch Face, the second Golden Color, the third Elephant Multitude, and the fourth Nikura (translated into Sui as 'Separately Formed'). When the four sons first arrived north of the Snow Mountains, they halted their carriage under the luxuriant branches of a great tree; therefore, they were named Śākyaja. Now saying Sheyi is certainly an erroneous abbreviation of the Sanskrit. The Mahīśāsaka Vinaya states: 'Near the north of the Snow Mountains, at the Śākya forest, they built a city and erected residences.' Moreover, when King Bimbisāra first asked the Buddha in which country he was born, the Buddha said he was born in the Śākya country. (Examining this now: the country was definitely named after the tree, and the clan was named after the country.) ○ The Fayuan [zhulin] states: 'Śākya is a noble surname of the Western Regions.'