According to the rules and regulations of fruitive activities, there is a need to offer periodical food and water to the forefathers of the family. This offering is performed by worship of Viṣṇu, because eating the remnants of food offered to Viṣṇu can deliver one from all kinds of sinful actions. Sometimes the forefathers may be suffering from various types of sinful reactions, and sometimes some of them cannot even acquire a gross material body and are forced to remain in subtle bodies as ghosts. Thus, when remnants of prasādam food are offered to forefathersby descendants, the forefathers are released from ghostly or other kinds of miserable life. Such help rendered to forefathers is a family tradition, and those who are not in devotional life are required to perform such rituals. One who is engaged in the devotional life is not required to perform such actions. Simply by performing devotional service, one can deliver hundreds and thousands of forefathers from all kinds of misery. It is stated in the Bhāgavatam (11.5.41):
devarṣi-bhūtāpta-nṛṇāṁ pitṟṇāṁ
na kiṅkaro nāyam ṛṇī ca rājan
sarvātmanā yaḥ śaraṇaṁ śaraṇyaṁ
gato mukundaṁ parihṛtya kartam
"Anyone who has taken shelter of the lotus feet of Mukunda, the giver of liberation, giving up all kinds of obligation, and has taken to the path in all seriousness, owes neither duties nor obligations to the demigods, sages, general living entities, family members, humankind or forefathers." Such obligations are automatically fulfilled by performance of devotional service to the Supreme Personality of Godhead.
(Bhagavad-Gita-----1:41-----purport).

There are many good examples in the lives of the great devotees of the Lord of those who became indifferent to the rituals of the Vedas simply by devotional service to the Lord. When a person factually understands Kṛṣṇa and his relationship with Kṛṣṇa, he naturally becomes completely indifferent to the rituals of fruitive activities, even though an experienced brāhmaṇa. Śrī Mādhavendra Purī, a great devotee and ācārya in the line of the devotees, says:
sandhyā-vandana bhadram astu bhavato bhoḥ snāna tubhyaṁ namo
bho devāḥ pitaraś ca tarpaṇa-vidhau nāhaṁ kṣamaḥ kṣamyatām
yatra kvāpi niṣadya yādava-kulottaṁsasya kaṁsa-dviṣaḥ
smāraṁ smāram aghaṁ harāmi tad alaṁ manye kim anyena me
"O my prayers three times a day, all glory to you. O bathing, I offer my obeisances unto you. O demigods! O forefathers! Please excuse me for my inability to offer you my respects. Now wherever I sit, I can remember the great descendant of the Yadu dynasty (Kṛṣṇa), the enemy of Kaṁsa, and thereby I can free myself from all sinful bondage. I think this is sufficient for me."
(Bhagavad-Gita-----2:52-----purport).

The Vedic rites and rituals are imperative for neophytes: comprehending all kinds of prayer three times a day, taking a bath early in the morning, offering respects to theforefathers, etc. But when one is fully in Kṛṣṇa consciousness and is engaged in His transcendental loving service, one becomes indifferent to all these regulative principles because he has already attained perfection. If one can reach the platform of understanding by service to the Supreme Lord Kṛṣṇa, he has no longer to execute different types of penances and sacrifices as recommended in revealed scriptures. And, similarly, if one has not understood that the purpose of the Vedas is to reach Kṛṣṇa and simply engages in the rituals, etc., then he is uselessly wasting time in such engagements. Persons in Kṛṣṇa consciousness transcend the limit of śabda-brahma, or the range of the Vedas and Upaniṣads.
(Bhagavad-Gita-----2:52-----purport).

The friends of the twice-born families are those who are born in the families of brāhmaṇas, kṣatriyas and vaiśyas, or the spiritually cultured families, but who themselves are not equal to their forefathers. Such descendants are not recognized as such, for want of purificatory achievements. The purificatory activities begin even before the birth of a child, and the seed-giving reformatory process is called Garbhādhāna-saṁskāra. One who has not undergone such Garbhādhāna-saṁskāra, or spiritual family planning, is not accepted as being of an actual twice-born family. The Garbhādhāna-saṁskāra is followed by other purificatory processes, out of which the sacred thread ceremony is one. This is performed at the time of spiritual initiation. After this particular saṁskāra, one is rightly called twice-born. One birth is calculated during the seed-giving saṁskāra, and the second birth is calculated at the time of spiritual initiation. One who has been able to undergo such important saṁskāras can be called a bona fide twice-born.
(Srimad Bhagavatam-----1:4:25-----purport).

There is no possibility of such methodical chanting of the Vedic hymns by the so-called brāhmaṇas or priests of the present age. The untrained descendants of the twice-born families are no more like their forefathers, and thus they are counted amongst the śūdras, or once-born men. The once-born man is unfit to chant the Vedic hymns, and therefore there is no practical utility of chanting the original hymns.
(Srimad Bhagavatam-----1:12:34-----purport).

The most authentic Vedic literature, accepted by the great Indian ācāryas like Śaṅkara, Rāmānuja, Madhva, Viṣṇu Svāmī, Nimbārka and Caitanya and studied by all important personalities of the world, is the Bhagavad-gītā, in which the worship of the demigods and their respective residential planets are mentioned. The Bhagavad-gītā (9.25) affirms:
yānti deva-vratā devān
pitṟn yānti pitṛ-vratāḥ
bhūtāni yānti bhūtejyā
yānti mad-yājino 'pi mām
"The worshipers of demigods reach the respective planets of the demigods, and the worshipers of forefathers reach the planets of the forefathers. The gross materialist remains in the different material planets, but the devotees of the Lord reach the kingdom of God."
(Srimad Bhagavatam-----2:3:11-----purport).

For pure devotees of the Lord who are completely satisfied with the transcendental loving service of the Lord, there is hardly any necessity to visit the various places of pilgrimage. But those who are not so advanced have the prescribed duties of visiting pilgrimage sites and regularly performing the rituals. The part of the princely order of the Yadu dynasty who went to Prabhāsa performed all duties to be done in a place of pilgrimage and offered their pious actions to their forefathers and others.
As a rule, every human being is indebted to God, the demigods, great sages, other living entities, people in general, forefathers, etc., for various contributions received from them. Thus everyone is obliged to repay the debt of gratitude.
(Srimad Bhagavatam-----3:3:26-----purport).

A person in the renounced order of life, a sannyāsī, is also called a sādhu because he renounces everything—his home, his comfort, his friends, his relatives, and his duties to friends and to family. He renounces everything for the sake of the Supreme Personality of Godhead. A sannyāsī is generally in the renounced order of life, but his renunciation will be successful only when his energy is employed in the service of the Lord with great austerity. It is said here, therefore, bhaktiṁ kurvanti ye dṛḍhām. A person who seriously engages in the service of the Lord and is in the renounced order of life is a sādhu. A sādhu is one who has given up all responsibility to society, family, and worldly humanitarianism, simply for the service of the Lord. As soon as he takes his birth in the world, a person has so many responsibilities and obligations—to the public, to the demigods, to the great sages, to the general living beings, to his parents, to the family forefathers and to many others. When he gives up all such obligations for the sake of the service of the Supreme Lord, he is not punished for such renunciation of obligation. But if for sense gratification a person renounces all such obligations, he is punished by the law of nature.
(Srimad Bhagavatam-----3:25:22-----purport).

The gṛhamedhīs, who want to continue a prosperous materialistic way of life, generally worship the demigods or the forefathers by offering piṇḍa, or respectful oblations. Such persons are bereft of Kṛṣṇa consciousness and are not interested in devotional service to the Lord. This kind of so-called pious and religious man is the result of impersonalism.
(Srimad Bhagavatam-----3:32:2-----purport).

One who reaches this stage performs the arcanā process in devotional service. Anyone, whether a gṛhastha or a sannyāsī, can keep small Deities of the Lord suitably packed or, if possible, installed, and thus worship the Deities of Rādhā-Kṛṣṇa, Sītā-Rāma, Lakṣmī-Nārāyaṇa, Lord Jagannātha or Śrī Caitanya Mahāprabhu by offering food prepared in ghee and then offering the sanctified prasāda to the forefathers, demigods and other living entities as a matter of routine daily work. All the centers of our Kṛṣṇa consciousness movement have Deity worship programs very nicely going on in which food is offered to the Deity and distributed to the first-class brāhmaṇas and Vaiṣṇavas and even to the people in general. This performance of sacrifice brings complete satisfaction. The members of the Kṛṣṇa consciousness movement engage daily in such transcendental activities. Thus in our Kṛṣṇa consciousness movement there is no question at all of killing animals.

(Srimad Bhagavatam-----7:15:11-----purport).

“By offering oblations with ghee, one satisfies the demigods. By studying the Vedas, one performs brahma-yajña, which satisfies the great sages. Offering libations of water before one's forefathers is called pitṛ-yajña. By offering tribute, one performs bhūta-yajña. By properly receiving guests, one performs nṛ-yajña.” These are the five yajñas that liquidate the five kinds of indebtedness—indebtedness to the demigods, great sages, forefathers, living entities and common men. Therefore one has to perform these five kinds of yajñas. But when one takes to the saṅkīrtana-yajña (the chanting of the Hare Kṛṣṇa mantra), one does not have to perform any other yajña.
(Sri Caitanya Caritamrta-----2:22:141-----purport).

In this way, we are indebted to the demigods, to the forefathers, to the sages, to the animals and to society in general. It is our duty to repay them all by proper discharge of service. But by the one stroke of devotional service, if someone gives up all obligations and simply surrenders unto the Supreme Personality of Godhead, he is no longer a debtor, nor obliged to any other source of benefit.
(Nectar of Devotion).