Dama-pradhāna-dharma (Self-restraint as the Root of Dharma) — Śānti-parva 154
यथाकृता च भूतेषु प्राप्पते सुखदु:खिता । गृहीत्वा जायते जन्तुर्दु:खानि च सुखानि च
yathākṛtā ca bhūteṣu prāpyate sukhaduḥkhitā | gṛhītvā jāyate jantur duḥkhāni ca sukhāni ca ||
यथाकृतं च भूतेषु प्राप्नोति सुखदुःखिताम् । गृहीत्वा जायते जन्तुः दुःखानि च सुखानि च ॥
भीष्म उवाच
Bhīṣma teaches karmic moral causality: the happiness and suffering one experiences are shaped by how one has acted toward other beings; the embodied self is born bearing the results of past deeds and therefore encounters both pleasure and pain.
In the Śānti Parva’s instruction on dharma, Bhīṣma continues advising Yudhiṣṭhira by explaining why beings undergo mixed experiences in life—because they are born carrying the consequences of prior actions.