Mahabharata 7.8.10

अश्मसारमयं नूनं हृदयं सुदृढं ममयच्छ्रुत्वा निहतं द्रोणं शतधा न विदीर्यते

aśmasāramayaṃ nūnaṃ hṛdayaṃ sudṛḍhaṃ mamayacchrutvā nihataṃ droṇaṃ śatadhā na vidīryate

Our plain-language meaning of this verse is waiting for scholar review.