In plain words
Dharmaja performed his mother's last rites. He had his grandson Parīkṣit crowned. Then, with his four brothers and Draupadī following, he set out for the Himālayas. Dharmaja walked ahead and they followed him. On the way, one after another, they left their bodies. In the end, a small puppy was left with Dharmaja. Indra stood at the gate of heaven and invited Dharmaja in. ‘If you let in the puppy that has followed me too, I will come’, said Dharmaja. In his eyes all beings were equal. Pleased with Dharmaja's devotion to Dharma, Yama Dharmarāja, who was there in the form of a dog, took on his true form.
Then Dharmaja visited hell. Hardly had he gone there and stayed ten minutes when the beings suffering there felt great relief. Their agony vanished. Overflowing with joy, they prayed, ‘Dharmaja! Stay on here and give us comfort.’ Then Dharmaja, ‘It is not I who protect you. ‘Dharmo rakṣati rakṣitaḥ’: those who protect Dharma, Dharma itself protects’, he said.
Because Dharmarāja never strayed from Dharma in any situation, he lived up to his name. People today say of themselves, ‘I am Prahlāda’, ‘I am Rāma’. Merely taking the names is not enough. You must keep in your heart the qualities fitting those names, and live up to your names.