I have been looking for more details about the rishi so have managed to piece together some information about him.
He seems to be one of the rishis in the disciplic succession for the Shukla Yajurveda as mentioned in the Brihadaranyaka Upanishad:
From Yājñavalkya. Yājñavalkya from Uddālaka. Uddālaka from Aruṇa. Aruṇa from Upaveśi. Upaveśi from Kuśri. Kuśri from Vajaśravas. He from Jihvāvat, the son of Badhyoga. He from Asīta, the son of Varṣagaṇa. He from Harita Kaśyapa. He from Śilpa Kaśyapa. This one from Kaśyapa, the son of Nidhruva. He from Vāc. She from Ambhiṇī. She from the sun. These white Yajuses received from the sun are explained by Yājñavalkya Vājasaneya.
The Kaumarika Khand of Skanda Puran mentions about a group of accomplished brahmins who were extolled by Narad Muni who were led by Harita to even Surya Deva who came down to test them in the form a Brahmin:
Thereafter, an old Brāhmaṇa of great splendour was seen by my Brāhmaṇas. He was wearing matted hair that had become tawny in colour on account of the holy baths thrice a day. Thereupon, those Brāhmaṇas, the chief of whom was Hārīta, became excessively delighted. Their eyes beamed like full-blown lotuses. They rose up from their Vedic sacrificial hall and rushed towards that Brāhmaṇa.
Apparently they were advised to visit Badarikashram by Narad and Harita led them as per the same section:
Without daring, prosperity cannot be obtained at all. Hence, O Nārada, I will go there at your instance. I have under me twenty-six thousand Brāhmaṇas. They are all engaged in the six holy acts (i.e. duties) of Brāhmaṇas (viz. study and teaching of Vedas, performance of sacrifice by oneself or through others, acceptance of gifts and giving religious gifts). They are devoid of greed and arrogance or fraud. I will come along with them. This is excellent in my opinion.”
Skanda Purana Tirtha Mahatmya section mentions about him living near the Saubhāgyakūpikā Tirtha where his wife was once enamored by Kamdeva:
Formerly there was a Brāhmaṇa well-known by the name Hārīta. He performed his penance there in his Vānaprastha stage. He had a chaste lady as his wife. She possessed beauty and other exquisite qualities. Like Lakṣmī, the wife of the enemy of Madhu (Viṣṇu) she was the most beautiful lady in all the three worlds. She was well-known by the name Pūrṇakalā. She had well-developed good qualities......Then on seeing the lady of splendid countenance, Kāmadeva too was hit in his heart by his own flowery arrows.
The rishi's wife forgets to return home listening to the sweet words of Kama so when the sage starts looking for her he finds them talking and in his anger curses them thus:
O sinner, you have afflicted my wife thus with the arrows. She has been an innocent chaste lady devoted loyally to her husband. She has been hit by you and made to stand with face down with excessive bashfulness. Hence you will be overcome with the fell disease of leprosy. You will be unpleasant to see. Even your wives will forsake you. On seeing you, she became enamoured of you. Thereby she transgressed her duty. She shall become senseless resembling a rock.”
The Uttarardha Section of the same Purana mentions him pleasing Surya and asking for the boon to regain his youth so that he could perfom even more penance:
Here at Vārāṇasī formerly an old great sage named Hārīta propitiated the Sun-god for the sake of great abundance of penance. Endowed with firm devotion, he installed the image of the Sun towards the south of Viśālākṣī. The image had all auspicious characteristics and was intended to bestow auspiciousness. Bradhna (the Sun-god), being pleased with him, granted a boon unto that old austere sage. He said, “Do not delay. Request me. What boon should be given by me to you?”
That sage chose the boon from the delighted Sun-god, the jewel of firmament: “If the Lord is pleased, grant me youth once again. Since I have reached old age, I have no capacity to perform penance. Having regained my youth, I shall perform an excellent penance. Thereafter that deity Ādītya who dispels senility is remembered as Vṛddhāditya, because he had been propitiated by the old sage Hārīta.
As corroborated by the Samhita by his name, he is also mentioned as one of the law-givers:
The following are the Law-givers of Dharmaśāstras: Manu, Atri, Viṣṇu, Hārīta, Yājñavalkya, Uśanas, Aṅgiras, Yama, Āpastaṃba, Saṃvarta, Kātyāyana, Bṛhaspati, Parāśara, Vyāsa, Śaṅkha, Likhita, Dakṣa, Gautama, Śātātapa and Vasiṣṭha.
Apparently he has also written on medicine as this discussion on the Charak & Sushruta Samhita states:
Suśruta refers to the six treatises of the great sages on medicine (satṣu kāyacikitsāsu). According to Ḍalhaṇa, these are the saṃhitās of Agniveśa, Bhela, Jātukarṇa, Parāśara, Hārīta and Kṣārapāṇi.
Will keep adding as I find more about him!
