Yudhishthira called Dharma the best friend in the Yaksha Prashna episode of the Mahabharata. When asked by the Yaksha, "Who is the best friend of a dying man?", Yudhishthira replied, "Dharma is the only friend who accompanies one in death."

This emphasizes the Hindu concept of Dharma as the principle of righteousness, duty, and cosmic order. While family, friends, and possessions are left behind at death, the consequences of one's actions (Dharma) follow the soul into the next life, shaping its future. Therefore, Dharma acts as the ultimate and unwavering companion.

Sources:

• Wisdom Library explanation of Dharma