Mahabharata — Anushasana Parva, Shloka 26
Viṣṇu-sahasranāma—Yudhiṣṭhira’s Inquiry and Bhīṣma’s Recitation (विष्णोर्नामसहस्रम्)
वहाँ पुण्योदका नामसे प्रसिद्ध नदी है, जो यमलोकनिवासियोंके लिये विहित है। उसमें अमृतके समान मधुर, शीतल एवं अक्षय जल भरा रहता है ।।
yama uvāca | tatra puṇyodakā nāma prasiddhā nadī yā yamalokanivāsibhyo vihitā | tasyāṃ amṛtasamaṃ madhuraṃ śītalam akṣayaṃ ca jalaṃ pūrṇaṃ tiṣṭhati || sa tatra toyaṃ pibati pānīyaṃ yaḥ prayacchati | pradīpasya pradānena śrūyatāṃ guṇavistaraḥ | yo hiha jaladānaṃ karoti sa paralokaṃ gatvā tasyā nadījalasya pānaṃ labhate | atha pradīpadānāt yaḥ atiriktataraḥ lābhaḥ sa śrūyatām ||
阎摩说道：那里有一条著名的河，名为“福水河”（Puṇyodakā），为阎摩之界的众生所设。河中充满如甘露般的水——甘甜、清凉、无有穷尽。凡在此世施与饮水者，至彼世便得饮此河之水。如今且听布施明灯（dīpa-dāna）所生功德的详说。
यम उवाच
Educational Q&A
Acts of practical charity—especially giving drinking water—generate lasting merit that returns to the giver in the afterlife; the passage also introduces the superior or expanded merits associated with gifting a lamp (dīpa-dāna).
Yama describes a sacred river in his realm, Puṇyodakā, whose nectar-like water is enjoyed by those who donated water while alive; he then transitions to explain, in greater detail, the fruits of lamp-giving.