The Law Code of Yājñavalkya 1.10.174

1.10.174

iti vacanāt, vaṃśaparamparāyātasamācaraṇena vyavasthā, evaṃvidhaviṣayavyatirekeṇāsya vacanasya viṣāyāntarābhāvāt | yatra punaḥ śāstrato na vyavasthā nāpy ācāras tatra ātmanas tuṣṭir eva vā (MDh 2.6) iti vacanād ātmanas tuṣṭir eva vyavasthāpikā, yathā garbhāṣṭame 'ṣṭame vābde (YDh 1.14) iti | mātuḥ sapiṇḍīkaraṇe 'pi viruddhāni vākyāni dṛśyante tatra pitāmahyādibhiḥ sārdhaṃ sapiṇḍīkaraṇaṃ smṛtam | tathā bhartrāpi bhāryāyāḥ svamātrādibhiḥ saha sapiṇḍīkaraṇaṃ kartavyam iti paiṭhīnasir āha |

The determination is made by the practice handed down through the lineage tradition, because apart from such matters, this text has no other scope. Where, however, there is no determination by scripture and no customary practice, then by the text "or satisfaction of one's own self" (MDh 2.6), the satisfaction of one's own self alone is the determinant, as in: "in the eighth year from conception, or in the eighth year [from birth]" (YDh 1.14). In the sapīṇḍīkaraṇa of a mother as well, conflicting statements are seen. There, sapīṇḍīkaraṇa together with the paternal grandmother and the rest is remembered in tradition. Likewise, sapīṇḍīkaraṇa of a wife should also be performed by the husband along with his own mother and others; thus says Paiṭhīnasi: