Anuśāsana-parva Adhyāya 112: Dharma as the sole companion; karmic witnesses; rebirth sequences
Bṛhaspati–Yudhiṣṭhira Saṃvāda
मनसश्न पृथिव्याश्व पुण्यास्तीर्थास्तथापरे । उभयोरेव यः स्नायात् स सिद्धि शीघ्रमाप्तुयात्
Bhīṣma said: “Thus there are many merit-filled tīrthas upon the earth, and others within the mind as well. Whoever bathes in both kinds—outer and inner—will swiftly attain siddhi, the supreme accomplishment of reaching the Highest Self.”
भीष्म उवाच