Adhyāya 166: Kṛtaghna-doṣa (कृतघ्नदोषः) — the fault of ingratitude and the limits of expiation
नैव कन्या न युवतिर्नामन्त्रज्ञो न बालिश:
naiva kanyā na yuvatir nāmantrajño na bāliśaḥ
Bhīṣma said: “One should not (treat as fit for trust or counsel) a mere girl, nor a young woman, nor one who is unversed in mantras, nor a foolish person.”
भीष्म उवाच
The verse stresses discernment in seeking guidance: counsel should be taken from those who are mature, knowledgeable, and wise, not from the inexperienced or the foolish.
In Śānti Parva, Bhīṣma is instructing Yudhiṣṭhira on dharma and practical governance; here he lists categories of persons regarded (in that traditional context) as unsuitable for giving reliable counsel.