Mahabharata — Anushasana Parva, Shloka 104
आचारप्रशंसा
Praise of Ācāra as the Basis of Longevity, Fame, and Prosperity
अड््गुष्ठस्य च यन्मध्यं प्रदेशिन्याश्व॒ भारत । तेन पित्र्याणि कुर्वीत स्पृष्टवापो न्न्यायत: सदा
aṅguṣṭhasya ca yan madhyaṃ pradeśinyāś ca bhārata | tena pitryāṇi kurvīta spṛṣṭvāpo nyāyataḥ sadā bhārata ||
ビーシュマは言った。「バラタよ、親指と人差し指の間の部位は、ピトリ・ティールタ（pitṛ-tīrtha）—祖霊のための聖点—と呼ばれる。それを用い、聖典の定める作法に従って水を取り、常に祖霊（ピトリ）への儀礼を正しく行うべきである。」
भीष्म उवाच
Educational Q&A
Bhishma teaches a practical rule of ritual conduct: the space between the thumb and index finger is designated as the pitṛ-tīrtha, and water taken/handled through that point should be used to perform ancestral rites properly and regularly.
In Anuśāsana Parva, Bhishma instructs Yudhiṣṭhira on dharma, including śrāddha and pitṛ-karmas. Here he specifies the bodily ‘tīrtha’ (hand position) used when offering water to the ancestors, emphasizing correct procedure (nyāyataḥ).