What are the available references in The Vedas for the divine sage Narada? Would appreciate the exact locations / coordinates (like the mantra with number, recension, publication etc.)
Talking about Samhitas of Vedas, Narada is a seer of 33 mantras of 13th Suktas of 8th Mandala of Rigveda but there is no mention of Narada in the text of Rigveda.
Narada is mentioned in Atharva Veda Samhita
तं वृक्षा अप सेधन्ति छायां नो मोप गा इति ।
यो ब्राह्मणस्य सद्धनमभि नारद मन्यते ॥९॥
Taṃ vṛkṣā apa sedhanti chāyāṃ no mopa gā iti ।
Yo brāhmaṇasya saddhanamabhi nārada manyate ॥9॥
9. The very trees repel the man, and drive him from their sheltering shade, Whoever claims, O Nārada, the treasure that a Brāhman owns.
चरेदेवा त्रैहायणादविज्ञातगदा सती ।
वशां च विद्यान् नारद ब्राह्मणास्तर्ह्येष्याः ॥१६॥
Caredevā traihāyaṇādavijñātagadā satī ।
Vaśāṃ ca vidyān nārada brāhmaṇāstarhyeṣyāḥ ॥16॥
16. Thus after three years may she go, speaking what is not under- stood. He, Nārads! would know the Cow, then Brāhmans must be sought unto.
देवा वशामयाचन् यस्मिन्न् अग्रे अजायत ।
तामेतां विद्यान् नारदः सह देवैरुदाजत ॥२४॥
devā vaśāmayācan yasminn agre ajāyata ।
tāmetāṃ vidyān nāradaḥ saha devairudājata ॥24॥
24. The Deities begged the Cow from him with whom at first she was produced: Her, this one, Nārada would know: with Deities he drove her forth.
Similarly he is mentioned at 12.4.41,42,43,45
yā vaśā udakalpayan devā yajñādudetya । tāsāṃ viliptyaṃ bhīmāmudākuruta nāradaḥ ॥41॥
41. Nārada chose the terrible Vilipti out of all the cows Which the Gods formed and framed when they had risen up from sacrifice
tāṃ devā amīmāṃsanta vaśeyā3 avaśeti । tāmabravīn nārada eṣā vaśānāṃ vaśatameti ॥42॥
42. The Gods considered her in doubt whether she were a Cow or not. Nārada spake of her and said, The veriest Cow of cows is she.
kati nu vaśā nārada yāstvaṃ vettha manuṣyajāḥ । tāstvā pṛchāmi vidvāṃsaṃ kasyā nāśnīyādabrāhmaṇaḥ ॥43॥
43. How many cows, O Nārada, knowest thou, born among mankind I ask thee who dost know, of which must none who is no Brāhman eat?
namaste astu nāradānuṣṭhu viduṣe vaśā । katamāsāṃ bhīmatamā yāmadattvā parābhavet॥45॥
45. Homage, O Nārada, to thee who hast quick knowledge of the cows. Which of these is the direst, whose withholding bringeth death to man?
Apart from Samhita, he is mentioned in Aitareya Brahmana 18.104.22.168 and 8.4.7 and also in Chhandogya Upanishad several times.
Research credit: संस्कृत साहित्य मैं देवरिषि नारद का स्वरुप वेदों से श्रीहर्ष तक की कृतियों के विशिष्ठ सन्दर्भ मैं, an article from Shodhganga, a reservoir of Indian theses.
ChhAndogya upanishad, the entire chapter 7 has instruction on brahman given to sage Narada by Sanatkumara.
It starts as below -
॥ सप्तमोऽध्यायः ॥ अधीहि भगव इति होपससाद सनत्कुमारं नारदस्तं होवाच यद्वेत्थ तेन मोपसीद ततस्त ऊर्ध्वं वक्ष्यामीति स होवाच ॥ ७.१.१ ॥
|| saptamo'dhyāyaḥ || adhīhi bhagava iti hopasasāda sanatkumāraṃ nāradastaṃ hovāca yadvettha tena mopasīda tatasta ūrdhvaṃ vakṣyāmīti sa hovāca || 7.1.1 ||
- Nārada went [for spiritual instruction] to Sanatkumāra and said, ‘Sir, please teach me.’ Sanatkumāra said to him: ‘First tell me what you know already. I’ll teach you from that point.’ Nārada said—