A term often met with in Sanskrit works, it means ‘one whose enemy is not born.’ It can refer to anyone who is so great and mighty that cannot be challenged by any as an enemy. More often it signifies a man who is so good, compassionate and noble that none hates him. Yudhiṣṭhira, the eldest of the Pāṇḍavas possessed such qualities and hence is known by that name.
The Bṛhadāraṇyaka Upaniṣad mentions one Ajātaśatru, the king of Kāśī (2.1) who was a great jñāni and who taught the ṛṣi Dṛpta Bālāki. The story is repeated in the Kauṣītaki Brāhmaṇa Upaniṣad (4.1) also.
According to the Buddhist lore, Ajātaśatru, the son of king Bimbisāra, and a ruler of Magadha committed several heinous crimes, repented of them and approached the Buddha for solace. It was on this occasion that the Buddha taught the well-known Sāmāññaphala Sutta.
The fortress of Pāṭalīputra, the capital of Magadha, was built by him.