Yàncóng 彥悰 (fl. late 7th c.), often distinguished as Cí’ēn 慈恩-sì Yàncóng to separate him from the homonymous earlier monks (the Suí translation-theorist 彥琮 彥琮 and the Táng disciple of 法琳 彥琮), was a Buddhist monk of Dà Cí’ēnsì 大慈恩寺 in Cháng’ān, active in the second half of the seventh century. He is best known for his role in the production of the standard biography of 玄奘 (Xuánzàng): retrieving the original five-juan draft (the běn 本) of 慧立 after the latter’s death, expanding it with annotations and supplementary documents, and presenting the completed ten-juan Dà Táng Dà Cí’ēnsì sānzàng fǎshī zhuàn (KR6r0043) to the throne in 688 (Wǔ Zétiān Chuígǒng 垂拱 4).
His own preface to the work explains the textual history: how he came across 慧立’s draft after the latter’s death, recognised its value, and undertook the supplementation. The relationship between 慧立’s original běn and 彥悰’s jiān 箋 (annotations / supplements) is one of the philological problems of the text — modern editors have generally been unable to disentangle the two layers cleanly.
The two graphs 彥琮 and 彥悰 are written with different second characters (琮 cóng, “jade tablet” / 悰 cóng, “joy”) and refer to entirely different persons. The Cí’ēn 彥悰 (with 悰) is the disciple of Xuánzàng’s circle. The Suí 彥琮 (with 琮) is the translation-theorist of the Bā bèi shí tiáo. The Táng 彥琮 (with 琮) is the disciple of 法琳.
He also compiled the 《集沙門不應拜俗等事》 Jí shāmén bùyīng bàisú děng shì (KR6r0141, T2108, 6 juan) — the comprehensive Tang documentary collection on the recurring imperial-Buddhist controversy over whether Buddhist monks should bow to the ruler and to their parents (覓 bùyīng bàisú 不應拜俗 = “ought not to do worldly obeisance”). The work is the principal documentary source for the whole Tang-period reconstitution of the Huìyuǎn argument (KR6r0137 Hóngmíng jí j. 5) for monastic non-prostration.