Sacrificial fire and brahamanas are considered to be the mouth of Vishnu

SB 8.16.9:
By worshiping the fire and the brāhmaṇas, a householder can achieve the desired goal of residing in the higher planets, for the sacrificial fire and the brāhmaṇas are to be considered the mouth of Lord Viṣṇu, who is the Supersoul of all the demigods

From Srila Prabhupada's purport:
"If one offers Me with love and devotion a leaf, a flower, fruit or water, I will accept it." Therefore, all these items may be offered in the sacrificial fire, and Lord Viṣṇu will be satisfied. Similarly, brāhmaṇa-bhojana, feeding of the brāhmaṇas, is also recommended, for when the brāhmaṇas eat sumptuous remnants of food after yajña, this is another way that Lord Viṣṇu Himself eats. Therefore the Vedic principles recommend that in every festival or ceremony one offer oblations to the fire and give sumptuous food for the brāhmaṇas to eat. By such activities, a householder may be elevated to the heavenly planets and similar places in the higher planetary systems.


SB 5.5.23
O respectful brāhmaṇas, as far as I am concerned, no one is equal or superior to the brāhmaṇas in this world. I do not find anyone comparable to them. When people know My motive, after performing rituals according to the Vedic principles they offer food to Me with faith and love through the mouth of a brāhmaṇa. When food is thus offered unto Me, I eat it with full satisfaction. Indeed, I derive more pleasure from food offered in that way than from the food offered in the sacrificial fire.

One must carry out the order of the Spiritual master and serve the brahamanas nicely

In the sixth canto after Indra offends his Guru Brhaspati , the demigods were being rapidly defeated by the demons who took advantage of their weak condition.Being thus bewidered and weakened the demigoids approached Lord Brahma for help.

On looking at their pitiable condition Lord Brahma said :

SB 6.7.22: Because of your misbehavior toward Bṛhaspati, you have been defeated by the demons. My dear demigods, since the demons were weak, having been defeated by you several times, how else could you, who were so advanced in opulence, be defeated by them?

All the opulence we possess is thus a result of the blessings of Guru and the Guru Parampara. By ourselves without the mercy of the Spiritual Master and the Guru Paramapara we are insignificant. Any of our endeavors is successful only because if the mercy and the backing of the entire Guru Parampara.

Prior to devotional life every endeavor of mine was plagued with many hurdles and resulted in miniscule success. However in devotional life anything done under the direction of authority is always successful. Pleasing our authorities means we follow their directions properly.When we do so we are able to recieve their blessings and mercy to complete the endeavor.

However if we offend our authority we will find ourselves completely weakened like the demigods.The mercy will be withdrawn automatically.

Further in the 8th canto,in the fight between the demons and the demigods after the nectar from the churning of the milk ocean is consumed by the demigods, Bali was defeated, and he died in the fight, but by the grace of Śukrācārya he regained his life. Thus he engaged himself in the service of Śukrācārya, his spiritual master.
The descendants of Bhṛgu, being pleased with him, engaged him in the Viśvajit-yajña. When this yajña was performed, from the fire of yajña came a chariot, horses, a flag, a bow, armor and two quivers of arrows. Mahārāja Prahlāda, Bali Mahārāja's grandfather, gave Bali an eternal garland of flowers, and Śukrācārya gave him a conchshell. Bali Mahārāja, after offering obeisances to Prahlāda, the brāhmaṇas and his spiritual master, Śukrācārya, equipped himself to fight with Indra and went to Indrapurī with his soldiers.Blowing his conchshell, he attacked the outskirts of Indra's kingdom. When Indra saw Bali Mahārāja's prowess, he went to his own spiritual master, Bṛhaspati, told him about Bali's strength, and inquired about his duty. Bṛhaspati informed the demigods that because Bali had been endowed with extraordinary power by the brāhmaṇas, the demigods could not fight with him. Bali was endowed with the blessings of the descendents of Bhrgupati, the blessings of his spritual master Sukracarya because he had pleased him and also his forefathers.

Agaian we see that by the mercy of the spiritual master and the brahamanas Bali Maharaj becomes very powerful.
Srila Prabhupada writes in this regard in 8.15.28:
We sing in our daily prayers, yasya prasādād bhagavat-prasādo yasyāprasādān na gatiḥ kuto 'pi **. By the pleasure of the spiritual master, one can get extraordinary power, especially in spiritual advancement. The blessings of the spiritual master are more powerful than one's personal endeavor for such advancement. Narottama dāsa Ṭhākura therefore says:


guru-mukha-padma-vākya, cittete kariyā aikya,āra nā kariha mane āśā **

Especially for spiritual advancement, one should carry out the bona fide order of the spiritual master. By the paramparā system, one can thus be endowed with the original spiritual power coming from the Supreme Personality of Godhead (evaḿ paramparā-prāptam imaḿ rājarṣayo viduḥ [Bg. 4.2]).