Mahabharata 11.9.2
वैशंपायन उवाच · vaiśaṃpāyana uvāca
एतच्छ्रुत्वा नरश्रेष्ठ चिरं ध्यात्वा त्वचेतनःसंजयं योजयेत्युक्त्वा विदुरं प्रत्यभाषत
etacchrutvā naraśreṣṭha ciraṃ dhyātvā tvacetanaḥsaṃjayaṃ yojayetyuktvā viduraṃ pratyabhāṣata
Our plain-language meaning of this verse is waiting for scholar review.