Snake

My Lord Nṛsiṁhadeva, please, therefore, cease Your anger now that my father, the great demon Hiraṇyakaśipu, has been killed. Since even saintly persons take pleasure in the killing of a scorpion or a snake, all the worlds have achieved great satisfaction because of the death of this demon. Now they are confident of their happiness, and they will always remember Your auspicious incarnation in order to be free from fear.
(SB 7.9.14)

When a man is snake-bitten he does not die immediately, but first becomes unconscious and remains in a comatose condition. Anyone who is in the material world is also sleeping, as he is ignorant of his actual self or his actual duty and his relationship with God. So materialistic life means that one is bitten by the snake of māyā, illusion, and thus, without any Kṛṣṇa consciousness, he is almost dead. Now the so-called dead man bitten by a snake can be brought back again to life by the chanting of some mantra.
(NOD 10)

Of weapons I am the thunderbolt; among cows I am the surabhi, givers of abundant milk. Of procreators I am Kandarpa, the god of love, and of serpents I am Vasuki, the chief.
(BG 10.28)

Of the many-hooded Nāgas I am Ananta, and among the aquatics I am the demigod Varuṇa. Of departed ancestors I am Aryamā, and among the dispensers of law I am Yama, the lord of death.
(BG 10.29)

It is said by Cāṇakya Paṇḍita that there are two envious living entities—the snake and the envious man. The envious man is more dangerous than a snake because a snake can be subdued by charming mantras or by some herbs, but an envious person cannot be pacified by any means.
(SB 4.22.11 purport)

In the Seventh Canto of the Śrīmad-Bhāgavatam you’ll find a statement by Nārada Muni that if there is a snake in your house, you should give it something to eat. Just see how your feelings can expand! You’ll care even for a snake, what to speak of other animals and human beings.
(JSD 6 Material Problems, Spiritual Solutions)

As Kṛṣṇa and Kāliya moved in a circle, the serpent gradually became fatigued, and his strength seemed to diminish considerably. Kṛṣṇa immediately pressed down the serpent ‘s hoods and jumped up on them. The Lord ‘s lotus feet became tinged with red from the rays of the jewels on the snake ‘s hoods. Then He who is the original artist of all fine arts, such as dancing, began to dance upon the hoods of the serpent, although they were moving to and fro. Upon seeing this, the denizens of the upper planets showered flowers, beat drums, played different types of flutes and sang various prayers and songs.
(KB 16)

Everyone knows that a snake is dangerous and poisonous, and when its hood is decorated with jewels, it is no less poisonous or dangerous. However qualified a materialist may be, he is no better than a snake decorated with jewels. One should therefore be careful in dealing with such materialists, just as one would be careful in dealing with a bejeweled serpent.
(CC Madhya 11.10)

The snake of separation bit Lakṣmīdevī, and its poison caused her death. Thus she passed to the next world. She went back home, back to Godhead.
(CC Adi 16.21)

A snake is a very fearful and dangerous animal because of his poison fangs, but if these fangs are broken, the appearance of a snake is no cause for fear. The yoga principles are meant to control the senses, but there is no scope for the senses of one engaged in the service of the Lord to be dangerous like snakes. These are the gifts of Śrī Caitanya Mahāprabhu.
(CC Adi 14.1 purport)

A person who has no connection with Kṛṣṇa consciousness may be a very great personality in so-called human society, but actually he is no better than a great animal. Such big animals are generally praised by other animals like dogs, hogs camels and asses. A person who does not lend his aural reception to hearing about the Supreme Personality of Godhead must be considered to have earholes like holes in a field. Although that person has a tongue, it is like the tongue of a frog, which unnecessarily creates a disturbance by croaking, inviting the snake of death. Similarly, a person who neither takes advantage of the dust of the lotus feet of great devotees nor smells the tulasī leaves offered to the lotus feet of the Lord must be considered dead even though he is supposedly working.
(CC Adi 13.123 purport)

There were many extraordinary activities performed by Murāri, a great devotee of Lord Caitanya Mahāprabhu. Sometimes in his ecstasy he would slap the cheek of a tiger, and sometimes he would play with a venomous snake.
(CC Adi 11.20)

Like a great mountain, the Lord stands as the abode for all moving and nonmoving living entities. He is the friend of the snakes because Lord Ananta is His friend. As a mountain has thousands of golden peaks, so the Lord was seen with the thousands of golden-helmeted hoods of Ananta-nāga; and as a mountain is sometimes filled with jewels, so also His transcendental body was fully decorated with valuable jewels. As a mountains is sometimes submerged in the ocean water, so the Lord is sometimes submerged in the water of devastation.
(SB 3.8.30)

In the Hari-bhakti-sudhodaya there is a statement about the incense which is offered in the temple: “When the devotees smell the good flavor of the incense which is offered to the Deity, they thus become cured of the poisonous effects of material contamination, as much as one becomes cured of a snakebite by smelling the prescribed medicinal herbs.” The explanation of this verse is that there is an herb found in the jungles which expert persons know how to use to revive the consciousness of one who is bitten by a snake. Simply by smelling that herb one becomes immediately relieved of the poisonous effects of the snakebite. The same example is applicable: when a person comes to visit the temple and smells the incense offered to the Deity, he is cured at that time from all his material contamination.
(NOD 9)