Narada Purana — Purva Bhaga, Shloka 14
Dharmānukathana
Narration of Dharma
कूपे पादफलं ज्ञेयं वाप्यां पद्माकरोन्मितम् । वापीशतगुणं प्रोक्तं कुल्यायां भूपतेः फलम् ॥ १४ ॥
kūpe pādaphalaṃ jñeyaṃ vāpyāṃ padmākaronmitam | vāpīśataguṇaṃ proktaṃ kulyāyāṃ bhūpateḥ phalam || 14 ||
知るべし、井戸の功徳は四分の一にすぎない。池の功徳は、そこに育つ蓮の群生（蓮座）の数に応じて量られる。大きな貯水池（ヴァーピー）は池の百倍の功徳を与えると説かれ、灌漑の水路（クルヤー）の功徳は王に帰すると宣言される。
Sanatkumara (in dialogue with Narada)
Vrata: none
Primary Rasa: shanta
Secondary Rasa: none
FAQs
It ranks the spiritual merit (puṇya) of water-supply works, teaching that sustaining life through accessible water is a high dharmic act, with greater and broader benefit yielding greater merit.
While not directly a bhakti-verse, it supports bhakti through dharma: serving beings (by providing water) is a sattvic offering aligned with devotion, since caring for creation is treated as pleasing to the Divine order upheld by Vishnu.
It reflects applied dharma-śāstra reasoning—measuring merit by public utility and scope—useful for ritual planning (kriyā) and governance (rāja-dharma), though it does not specifically teach a technical Vedanga like Vyākaraṇa or Jyotiṣa.