Story of Tṛṇabindu

A sage. This sage sat and did penance at a place called Ṛṣitīrtha. (Chapter 20, Padma Purāṇa).

Grandfather of Viśravas.

Viśravas, father of Rāvaṇa was the son of Māninī, daughter of Tṛṇabindu. There is a story about him in Uttara Rāmāyaṇa.

Once the sage Pulastya was doing penance in a secluded place in the Himālayas when a few Deva Gandharva women came to that place and disturbed his penance by their dances and noise. The angered sage gave a curse to that place saying that any woman coming to that place would become pregnant. Māninī, daughter of Tṛṇabindu went to this place unaware of the curse and got pregnant. She came weeping to her father and Tṛṇabindu immediately took his daughter to Pulastya and asked him to marry Māninī. Pulastya married Māninī and Viśravas was born to her.

How he cursed Hanūmān.

Once Hanūmān caught hold of a lion and elephant in fight and tied them each to a post on the two sides of the āśrama of Tṛṇabindu. When the sage stepped out from the hermitage, he was for a moment frightened by the sight of two mighty animals on the sides of his āśrama and knew by his divine powers that the perpetrator of that deed was Hanūmān and so he cursed him saying that he would lose all his divine powers forthwith. Hanūmān begged for relief and the sage said that he would regain his powers at the time of his going in search of Sītā when another member of his species would remind him of his lost divine powers. Hanūmān remained oblivious of his powers till the time when the monkeys were trying to leap to Laṅkā from the Mahendra mountain on the shores of Bhārata. Jāmbavān, a mighty monkey chief called Hanūmān to his side and made him understand the great powers latent in him. From that moment onwards Hanūmān regained his lost powers and became his old self. (See under Hanūmān).