Vyasadeva, following the order of his mother, Satyavati, begot three sons, two by the womb of Ambika and Ambalika, the two wives of his brother Vicitravirya, and the third by Vicitravirya's maidservant. These sons were Dhrtarastra, Pandu and Vidura

Expressions researched:
"After Vicitravirya's death, his mother, Satyavati, who was also the mother of Vyasadeva, asked Vyasadeva to beget children through the wives of Vicitravirya" |"By the order of his mother, Satyavati" |"Through the womb of the two wives and the maidservant of Vicitravirya, Vyasadeva begot Dhrtarastra, Pandu and Vidura" |"he begot three brilliant sons, whose names are Dhrtarastra, Pandu and Vidura"

SB Canto 1

By the order of his mother, Satyavatī, who was later married to Mahārāja Śantanu, and by the request of Bhīṣmadeva, the eldest son of Mahārāja Śantanu by his first wife, the Ganges, he begot three brilliant sons, whose names are Dhṛtarāṣṭra, Pāṇḍu and Vidura.

SB 1.9.6-7, Purport:

Bādarāyaṇa (Vyāsadeva): He is known as Kṛṣṇa, Kṛṣṇa-dvaipāyana, Dvaipāyana, Satyavatī-suta, Pārāśarya, Parāśarātmaja, Bādarāyaṇa, Vedavyāsa, etc. He was the son of Mahāmuni Parāśara in the womb of Satyavatī prior to her betrothal with Mahārāja Śantanu, the father of the great general Grandfather Bhīṣmadeva. He is a powerful incarnation of Nārāyaṇa, and he broadcasts the Vedic wisdom to the world. As such, Vyāsadeva is offered respects before one chants the Vedic literature, especially the Purāṇas. Śukadeva Gosvāmī was his son, and ṛṣis like Vaiśampāyana were his disciples for different branches of the Vedas. He is the author of the great epic Mahābhārata and the great transcendental literature Bhāgavatam. The Brahma-sūtras—the Vedānta-sūtras, or Bādarāyaṇa-sūtras—were compiled by him. Amongst sages he is the most respected author by dint of severe penances. When he wanted to record the great epic Mahābhārata for the welfare of all people in the age of Kali, he was feeling the necessity of a powerful writer who could take up his dictation. By the order of Brahmājī, Śrī Gaṇeśajī took up the charge of noting down the dictation on the condition that Vyāsadeva would not stop dictation for a moment. The Mahābhārata was thus compiled by the joint endeavor of Vyāsa and Gaṇeśa.

By the order of his mother, Satyavatī, who was later married to Mahārāja Śantanu, and by the request of Bhīṣmadeva, the eldest son of Mahārāja Śantanu by his first wife, the Ganges, he begot three brilliant sons, whose names are Dhṛtarāṣṭra, Pāṇḍu and Vidura. The Mahābhārata was compiled by Vyāsadeva after the Battle of Kurukṣetra and after the death of all the heroes of Mahābhārata. It was first spoken in the royal assembly of Mahārāja Janamejaya, the son of Mahārāja Parīkṣit.

SB Canto 9

Through the womb of the two wives and the maidservant of Vicitravīrya, Vyāsadeva begot Dhṛtarāṣṭra, Pāṇḍu and Vidura.

SB 9.22 Summary:

The sons of Pratīpa were Devāpi, Śāntanu and Bāhlīka. When Devāpi retired to the forest, his younger brother Śāntanu became the king. Although Śāntanu, being younger, was not eligible to occupy the throne, he disregarded his elder brother. Consequently, there was no rainfall for twelve years. Following the advice of the brāhmaṇas, Śāntanu was ready to return the kingdom to Devāpi, but by the intrigue of Śāntanu's minister, Devāpi became unfit to be king. Therefore Śāntanu resumed charge of the kingdom, and rain fell properly during his regime. By mystic power, Devāpi still lives in the village known as Kalāpa-grāma. In this Kali-yuga, when the descendants of Soma known as the candra-vaṁśa (the lunar dynasty) die out, Devāpi, at the beginning of Satya-yuga, will reestablish the dynasty of the moon. The wife of Śāntanu named Gaṅgā gave birth to Bhīṣma, one of the twelve authorities. Two sons named Citrāṅgada and Vicitravīrya were also born from the womb of Satyavatī by the semen of Śāntanu, and Vyāsadeva was born from Satyavatī by the semen of Parāśara, Vyāsadeva instructed the history of the Bhāgavatam to his son Śukadeva. Through the womb of the two wives and the maidservant of Vicitravīrya, Vyāsadeva begot Dhṛtarāṣṭra, Pāṇḍu and Vidura.

Vicitravīrya died of tuberculosis, and his wives, Ambikā and Ambālikā, had no issue. Therefore, after Vicitravīrya's death, his mother, Satyavatī, who was also the mother of Vyāsadeva, asked Vyāsadeva to beget children through the wives of Vicitravīrya.

SB 9.22.25, Translation and Purport:

Bādarāyaṇa, Śrī Vyāsadeva, following the order of his mother, Satyavatī, begot three sons, two by the womb of Ambikā and Ambālikā, the two wives of his brother Vicitravīrya, and the third by Vicitravīrya's maidservant. These sons were Dhṛtarāṣṭra, Pāṇḍu and Vidura.

Vicitravīrya died of tuberculosis, and his wives, Ambikā and Ambālikā, had no issue. Therefore, after Vicitravīrya's death, his mother, Satyavatī, who was also the mother of Vyāsadeva, asked Vyāsadeva to beget children through the wives of Vicitravīrya. In those days, the brother of the husband could beget children through the womb of his sister-in-law. This was known as devareṇa sutotpatti. If the husband was somehow unable to beget children, his brother could do so through the womb of his sister-in-law. This devareṇa sutotpatti and the sacrifices of aśvamedha and gomedha are forbidden in the age of Kali.

aśvamedhaṁ gavālambhaṁ

sannyāsaṁ pala-paitṛkam

devareṇa sutotpattiṁ

kalau pañca vivarjayet

(CC Adi 17.164)

"In this age of Kali, five acts are forbidden: the offering of a horse in sacrifice, the offering of a cow in sacrifice, the acceptance of the order of sannyāsa, the offering of oblations of flesh to the forefathers, and a man's begetting children in his brother's wife." (Brahma-vaivarta Purāṇa).