Question
Who is the first well known saint to mention Radha in his works?
Answer
As far as I know, Adi Shankaracharya mentions Sri Radha's name in his Yamunashtakam stotra Slokas 6 & 7. Sankskrit-Tamil translation available in this kamakoti website.
जलान्तकेलिकारिचारु राधिका ङ्गरागिणी स्वभर्तुरन्यदुर्लभाङ्गसङ्गतांशभागिनी स्वदत्तसुप्तसप्तसिन्धुभेदनातिकोविदा । धुनोतु मे मनोमलं कलिन्दनन्दिनी सदा ॥६॥
Jala-Anta-Keli-Kaari-Caaru-Raadhika-Angga-Raaginnii Sva-Bhartur-Anya-Durlabha-Angga-Sangga-Taamsha-Bhaaginii Sva-Datta-Supta-Sapta-Sindhu-Bhedana-Ati-Kovidaa | Dhunotu Me Mano-Malam Kalinda-Nandinii Sadaa ||6||
May Yamunā — Whose water is mixed with the cosmetics of sporting Rādhikā, Who enjoys the continuous touch of Her consort (Kṛṣṇa) which is a luxury for others, Who is mighty enough to penetrate the serene seven oceans, and Who is the daughter of Kalinda — washes the malice of my mind.[6]
जलच्युताच्युताङ्गरागलम्पटालिशालिनी विलोल राधिका कचान्तचम्पकालिमालिनी । सदावगाहनावतीर्णभर्तृभृत्यनारदा धुनोतु मे मनोमलं कलिन्दनन्दिनी सदा ॥७॥
Jala-Cyuta-Acyuta-Angga-Raaga-Lampatta-Ali-Shaalinii Vilola-Raadhikaa-Kaca-Anta-Campaka-Ali-Maalinii | Sada-Avagaahana-Avatiirnna-Bhartr-Bhrtya-Naaradaa Dhunotu Me Mano-Malam Kalinda-Nandinii Sadaa ||7||
May Yamunā — Who is full of damsels using fallen cosmetics of Acyuta (Kṛṣṇa) in Her water, Who has flowers from the braids of vibrant Rādhikā in Her water, Who is always taken as support by Nārada and other devotees of Her consort (Kṛṣṇa), and Who is the daughter of Kalinda — washes the malice of my mind.[7]
The celebrated Sri Vaishnava Acharya Vedanta Desikan(1268 A.D -1369 A.D)[Jayadeva Goswami's period is 1170 A.D-1245 A.D] mentions Radha's name in the 10th Canto of his Yadavabhyudayam, a poem on the life of Lord Krishna
dEvakee dhanujasThooNA dhivuyam DHAma vrajAngaNam ramA rADHAdhayScha ithi rASibhEdhairna bhidhyasE
There is no difference in the (states of) the Lord associated with Lakshmi (Ramaa), Radha or other consorts, or as being born as the Son of Devaki or being born from the Pillar as Narasimha, or living in Vaikunta or Vrindavan
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