Vidura, Bhishma and Drona with Bahlika are capable of understanding yourself and of speaking words of wisdom of wisdom which beneficial at the same time.
विदुरश्चैव भीष्मश्च द्रोणश्च सहबाह्निकः। श्रेयः समर्था विज्ञातुमुच्यमानास्त्वयानघ॥