If one's son becomes a Vaisnava in the family, he can deliver fourteen generations, up and down. That is the verdict. Not only verdict, this is the version in the Srimad-Bhagavatam

Expressions researched:
"fourteen generations"

Bhagavad-gita As It Is Lectures

Lord Nṛsiṁha-deva guaranteed, said, "My dear Prahlāda, not only your father, but your father's father, his father, up to fourteen generations, all are liberated. Because you are born in this family."

Lecture on BG 2.4-5 -- London, August 5, 1973:

Then, after many prayers, after pacifying the Lord... He was very angry. Then when He was little pacified, he asked, "My dear Lord, I can ask You one, another benediction. that my father was very, very staunch enemy of You. That was the cause of his death. Now I ask You kindly excuse him and give him liberation." This is Vaiṣṇava son. He did not ask anything for himself. And although he knew that his father was the greatest enemy, still, he is asking his benediction, "This poor fellow may be liberated." So Lord Nṛsiṁha-deva guaranteed, said, "My dear Prahlāda, not only your father, but your father's father, his father, up to fourteen generations, all are liberated. Because you are born in this family." So anyone who has become a Vaiṣṇava, a devotee of the Lord, he is giving the greatest service to the family. Because in relationship with him, his father, mother, anyone, they will be liberated. Just like we have got experience, if a person dies in the fight immaturely, his family is taken care of by the government. Similarly, to become a devotee is the greatest qualification. He has got everything. Yatra yogeśvaro hariḥ yatra dhanur-dharaḥ pārthaḥ (BG 18.78). When there is Kṛṣṇa and when there is devotee, all victory, all glories are there. That is guaranteed.

Srimad-Bhagavatam Lectures

As affection son, Prahlāda Mahārāja was anxious to know, "Whether my father will be liberated or not?" So this was confirmed by the Lord: "Not only your father, his father's father, his father, his father, up to fourteen generations, everyone is liberated—because a Vaiṣṇava son like you is born in this family."

Lecture on SB 3.25.44 -- Bombay, December 12, 1974:

So therefore Prahlāda Mahārāja, when he was requested, when he was, rather, offered any benediction he wanted to take from Nṛsiṁha-deva, he refused: "My dear Lord, please do not induce me in that way. I am born in a family, demonic family. To gain some material profit is my natural propensity. And You are the offerer. You are offering me. I can take anything from You. But this is not my business. Because I have rendered service to You, it does not mean that I will take some remuneration for You. This is business." Vaṇik. Sa vai vaṇik: "This is mercantile man's... But I am Your eternal servant. I do not expect any reward from You." But that Prahlāda Mahārāja, later on he asked Nṛsiṁha-deva, "My dear Lord, one thing I may ask from You." "What is that?" "Now, my father was atheist number one, and he has committed so many offenses at Your lotus feet. Now he is killed. So I want that he may be excused and given liberation." So he was already liberated. Still, as affection son, he was anxious to know, "Whether my father will be liberated or not?" So this was confirmed by the Lord: "Not only your father, his father's father, his father, his father, up to fourteen generations, everyone is liberated—because a Vaiṣṇava son like you is born in this family."

My point is: by serving the Supreme Lord, one gives the best service to the family, because if one becomes a Vaiṣṇava, pure Vaiṣṇava, the whole family, up to fourteen generations, they become liberated.

Lecture on SB 3.25.44 -- Bombay, December 12, 1974:

So my point is: by serving the Supreme Lord, one gives the best service to the family, because if one becomes a Vaiṣṇava, pure Vaiṣṇava, the whole family, up to fourteen generations, they become liberated. Therefore tīvreṇa bhakti-yogena. We should not divert our attention for any other service. We should simply concentrate for rendering service to the Supreme Lord. This is the conclusion. Tīvreṇa bhakti-yogena mano mayy arpitam. Mayi, "unto Me, the Supreme Lord, Kṛṣṇa." This is Kṛṣṇa consciousness. Always thinking of Kṛṣṇa, mayi. That will help. Tīvreṇa bhakti-yogena. Always... That is also advised in Bhagavad-gītā: man-manā, mad-bh... Man-manā bhava mad-bhaktaḥ. Your mind should be engaged always in Kṛṣṇa. Kṛṣṇa or Rāma, which form ever you like-Viṣṇu form, or Lord Viṣṇu, Nārāyaṇa, Kapiladeva. There are innumerable forms of God. Advaitam acyutam anādim ananta-rūpam (Bs. 5.33). So Rāma, Nṛsiṁha, Varāha, Kṛṣṇa, Kapiladeva, Balarāma—there are so many forms. So any one of Them, whichever you like... Everyone is... Just like Hanumān. He liked Rāmacandra forms, and Arjuna liked Kṛṣṇa's form. But there is no difference between Rāma and Kṛṣṇa. Rāmādi-mūrtiṣu kalā-niyamena tiṣṭhan nānāvatāram akarod bhuvaneṣu kintu (Bs. 5.39).

If one's son becomes a Vaiṣṇava in the family, he can deliver fourteen generations, up and down. That is the verdict. Not only verdict, this is the version in the Śrīmad-Bhāgavatam.

Lecture on SB 6.1.56-62 -- Surat, January 3, 1971, at Adubhai Patel's House:

So actual fact is Viṣṇu worship. That is the ultimate goal of Vedic civilization, but they do not know. Na te viduḥ svārtha-gatiṁ hi viṣṇum (SB 7.5.31). Their attention is diverted in so many demigods. The greatest disservice to the society, that "Here is another god, here..." Not only manufacturing a man-god, but they are advising that "Any god you can worship." No: Viṣṇu. Tad viṣṇoḥ paramaṁ padaṁ sadā paśyanti sūrayaḥ. This is Vedic mantra. Those who are sūrayaḥ, means advanced... Sūrayaḥ means... Sūrayaḥ and asūrayaḥ. Asūrayaḥ means demons. Viṣṇu-bhakto bhaved suraḥ: "Those who are devotees of Lord Viṣṇu, they are sura." Asuras tad-viparyayaḥ: "And those who are not Viṣṇu bhaktas, they are asuras." Just like Rāvaṇa was very great devotee of Lord Śiva; still, he was a asura. Hiraṇyakaśipu, he was a great devotee of Lord Brahmā, but he was considered asura. So anyone who is not devotee of Lord Viṣṇu, he is asura. That is the verdict. Asuras tad-viparyayaḥ. And this piṇḍa-dāna is offered oblations to the Viṣṇu. So if any man becomes a Vaiṣṇava, he is offering oblations to Viṣṇu every moment, so his forefathers are delivered without any trouble. Without any trouble. If one's son becomes a Vaiṣṇava in the family, he can deliver fourteen generations, up and down. That is the verdict. Not only verdict, this is the version in the Śrīmad-Bhāgavatam.

Festival Lectures

Despite so much troubles given by his father, still, Prahlāda Mahārāja begged from Narasiṁhadeva, "My Lord, my father has committed so many offenses. Kindly give him liberation." He did not ask anything for himself. So Narahari, Nṛsiṁha-deva, immediately said, "Why do you speak of your father? Your father's father, his father, fourteen generations—all liberated because a son like you is in this family."

Nrsimha-caturdasi Lord Nrsimhadeva's Appearance Day -- Bombay, May 5, 1974:

Kṛṣṇa consciousness is so nice that if one gets Kṛṣṇa consciousness, yaṁ labdhvā cāparaṁ lābhaṁ, aparaṁ lābhaṁ, any other benefit or gain is never considered. This is so nice. We are hankering after getting this, that, this, that, this, that, so many things. Dehi, dehi, dehi, dehi. But as soon as you get Kṛṣṇa consciousness, you will be satisfied. As Dhruva Mahārāja said, svāmin kṛtārtho 'smi varaṁ na yāce (CC Madhya 22.42). Just like Prahlāda Mahārāja. He was offered all benediction: "My dear Prahlāda, whatever you like, you can ask." He never asked anything. But he was so kind. That is the example of a Vaiṣṇava son in the family. Despite so much troubles given by his father, still, he begged from Narasiṁhadeva, "My Lord, my father has committed so many offenses. Kindly give him liberation." He did not ask anything for himself. So Narahari, Nṛsiṁha-deva, immediately said, "Why do you speak of your father? Your father's father, his father, fourteen generations—all liberated because a son like you is in this family." So this is the benefit. If a son becomes a pure Vaiṣṇava, devotee, he can deliver fourteen generation. That is a special prerogative because he is born in a certain family. So what we can give service to the family, nation, materially? If we become devotee, we can give best service to the nation, to the family, to the humanity. That is the philosophy.

1976 Conversations and Morning Walks

Liberation means—that is explained by Caitanya Mahāprabhu—to become devotee. That is liberation.

Morning Walk -- March 17, 1976, Mayapura:

Pañca-draviḍa: When it says in the śāstra that a hundred generations past and future of a devotee, they're liberated, what kind of liberation do they get?

Devotees: Fourteen.

Prabhupāda: Eh?

Pañca-draviḍa: What kind of liberation does the family get of a pure devotee?

Puṣṭa Kṛṣṇa: One who becomes a devotee, the statement is that fourteen generations of his family, past, present and future, become liberated. So what kind of liberation does the family members of a pure Vaiṣṇava get?

Prabhupāda: Liberation means—that is explained by Caitanya Mahāprabhu—to become devotee. That is liberation. To become.... To become a devotee is itself liberation. (break)

1977 Conversations and Morning Walks

How much faithful son Prahlāda Mahārāja was, this is the proof. Not that he was unfaithful to him. He knew it, that "Let my father's body be separated from his soul by the Lord. That is good for him." And still to confirm it he personally requested that "My father may be excused." "Why your father? Your father's father, his father, everyone, up to fourteen generations."

Discussion on Deprogrammers -- January 9, 1977, Bombay:

Rāmeśvara: Actually, one argument that they use... They have found an old Back to Godhead article that I think you wrote, Śrīla Prabhupāda. It was about Arjuna's position during the battle of Kurukṣetra, where he had to fight against his relatives. You were commenting that "So sometimes you may have to even kill your family members for Kṛṣṇa." So they take this magazine article, and they say that "Hare Kṛṣṇa leaders are teaching all the devotees to kill their parents." So this is an example of how they will distort everything.

Prabhupāda: That... You can distort anything. If there is expert distortion, it is...

Trivikrama: We can kill our parents even, like Prahlāda.

Prabhupāda: Yes, that is actually required. Prahlāda did not protest. It is a great sin, if your father is being killed before you, if you do not protest even, "Why you are killing?" not to give protection. But even if you do not, then you are not worthy son. So in that way Prahlāda Mahārāja was accused that in his presence his father was being killed. He did not protest, neither he... Rather, he was ready with the garland: (laughter) "As soon as my father is killed, immediately garland the Lord." So that is not the fact. And he is... Later on, he requested that "My father was a great offender. So kindly give him protection." So he's not..., that son. He knows... He knew that this, "My father is being killed by the nails of my Lord. It is his great fortune." Why shall he protest? He's seeing that "My father is being released from this material existence." Why shall he protest? And still to confirm it, he requested the Lord that "This, my rascal father made so many offenses..." But for him he did not ask anything, but he's such a good son that for demon father he requested. So how much faithful son he was, this is the proof. Not that he was unfaithful to him. He knew it, that "Let my father's body be separated from his soul by the Lord. That is good for him." And still to confirm it he personally requested that "My father may be excused." "Why your father? Your father's father, his father, everyone, up to fourteen generations."