阿彌陀經疏 1.95

1.95

經「難陀」者，《大威德陀羅尼經》云：有四：一者、但言難陀，此云喜；二、修難陀，此云善喜；三、阿難陀，此云歡喜；四、婆難陀，此云賢歡喜。今言難陀者，即佛之親弟，本姨母所生，孫陀羅婿也。所以名喜者，時王白淨適有悉達棄家入道，無人嗣位心常致憂，及生難陀，儀貌似兄堪繼洪業，故心生少喜。《別譯阿含》云：佛言：「我弟難陀者，能攝諸根不著六塵，飲食知節纔以止飢，故名難陀。」又《增一》云：身形端正與世殊異，諸根寂靜心不變易，故名難陀。《五百弟子本起經》云：由過去施僧煖浴室及洗一比丘僧，即得無垢身形端正色妙如華，又曾修飾辟支佛塔，又見迦葉佛塔建立剎柱安承露盤，以是諸因今生釋氏得為佛弟，有大人相，身長一丈五尺二寸。

As for "Nanda" in the sūtra: The Great Majestic Dhāraṇī Sūtra says there are four: first, simply called Nanda, translated here as "Joy"; second, Sunanda, translated here as "Good Joy"; third, Ānanda, translated here as "Delight"; fourth, Upananda, translated here as "Virtuous Delight". The one called Nanda here is the Buddha's own younger brother, born originally to his maternal aunt, and the husband of Sundarī. The reason he was named "Joy" is that at that time King Śuddhodana had just seen Siddhārtha abandon his family and enter the path, leaving no one to succeed to the throne, which caused him constant grief; when Nanda was born, his appearance resembled his elder brother's and he was fit to continue the great lineage, so a little joy arose in the king's heart. The Bieyi Za ahan jing says: The Buddha said, "My younger brother Nanda is able to restrain the sense faculties, does not cling to the six sense objects, and moderates his food and drink merely to stave off hunger; therefore he is named Nanda." Furthermore, the Ekottarika-āgama says: His body was well-proportioned and extraordinary in the world, his sense faculties were serene, and his mind was unswerving; therefore he was named Nanda. The Sūtra on the Original Deeds of the Five Hundred Disciples says: Because in the past he provided a warm bathhouse for the Saṅgha and washed a bhikṣu, he obtained an undefiled body, well-proportioned in form and with a complexion marvelous as a flower; furthermore, he had once repaired the stūpa of a pratyekabuddha, and upon seeing the stūpa of Kāśyapa Buddha, he erected a mast and installed dew-receiving basins; on account of all these causes, in this life he was born into the Śākya clan and became the Buddha's younger brother, possessing the marks of a great man, with a height of one rod, five feet, and two inches.