Mahabharata 8.24.75

कर्म सत्यं तपोऽर्थश्च विहितास्तत्र रश्मयःअधिष्ठानं मनस्त्वासीत्परिरथ्यं सरस्वती

karma satyaṃ tapo'rthaśca vihitāstatra raśmayaḥadhiṣṭhānaṃ manastvāsītparirathyaṃ sarasvatī

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