​MN 23 Vammika Sutta: The Ant-hill 

Thus have i heard. 

On one occasion the Blessed One was living at Savatthi in Jeta's Grove, Anathapindika's Park. Now on that occasion the venerable Kumara Kassapa was living in the Blind Men's Grove. Then at night, a certain deity of beautiful appearance who illuminated the whole of the Blind Men's Grove approached the venerable Kumara Kassapa and stood at one side. The deity said to him: "Bhikkhu, bhikkhu, this ant-hill fumes by night and flames by day. The brahmin said: 'Delve with the knife, thou wise one.' Delving with the knife, the wise one saw a bar: 'A bar, O venerable sir.' The brahmin then said: 'Throw out the bar; delve with the knife, thou wise one.' Delving with the knife, the wise one saw a toad: 'A toad, O venerable sir.'

​The brahmin said: "Throw out the toad; delve with the knife, thou wise one.' Delving with the knife, the wise one saw a fork: 'A fork, O venerable sir.' The brahmin said: 'Throw out the fork; delve with the knife, thou wise one.' Delving with the knife, the wise one saw a sieve: 'A sieve, O venerable sir.' The brahmin said: 'Throw out the sieve; delve with the knife, thou wise one.' Delving with the knife, the wise one saw a tortoise: 'A tortoise, O venerable sir.' The brahmin said: 'Throw out the tortoise; delve with the knife, thou wise one.' Delving with the knife, the wise one saw an axe and block: 'An axe and block, O venerable sir.'
The brahmin said: 'Throw out the axe and block; delve with the knife, thou wise one.' Delving with the knife, the wise one saw a piece of meat: 'A piece of meat, O venerable sir.' The brahmin said: 'Throw out the piece of meat; delve with the knife, thou wise one/ Delving with the knife, the wise one saw a Naga serpent: 'A Naga serpent, O venerable sir.' The brahmin said: 'Leave the Naga serpent; do not harm the Naga serpent; honor the Naga serpent.' "Bhikkhu, you should go to the Blessed One and ask him about this riddle. As the Blessed One tells you, so should you remember it. Bhikkhu, other than the Tathagata or a disciple of the Tathagata or one who has learned it from them, I see no one in this world with its gods, its Maras,  its Brahmas,  its recluses and brahmins, its princes and its people, whose explanation of this riddle might satisfy the mind." That is what was said by the deity, who vanished at once.

When the night was over, venerable Kumara Kassapa went to the Blessed One. After paying homage to him, he sat down at one side and told the Blessed One what had occurred. Kassapa asked: "Venerable sir, what is the ant-hill, what is fuming by night and what is flaming by day? Who is the brahmin, who is the wise one? What is the knife, what is the delving, what is the bar, what is the toad, what is the fork, what is the sieve, what is the tortoise, what is the axe and block, what is the piece of meat, what is the Naga serpent?"

Buddha replied: "Bhikkhu, the ant- hill is a symbol for this body, made of material form, consisting of the four great elements, procreated by a mother and father, supported by boiled rice and porridge, subject to impermanence, to being wearing away and erosion, to dissolution and disintegration. What one thinks and ponders by night based upon one's actions during the day is the 'fuming by night.' The actions one undertakes during the day by body, speech, and mind after thinking and pondering by night is the 'flaming by day.' The brahmin is a symbol for the Tathagata, accomplished and fully enlightened. The wise one is a symbol for a bhikkhu in higher training. The knife is a symbol for noble wisdom. The delving is a symbol for the arousing of energy. The bar is a symbol for ignorance. Throw out the bar means abandon ignorance. Delve with the knife, thou wise one. This is the meaning. "

"The toad is a symbol for the despair due to anger. Throw out the toad means abandon despair due to anger. Delve with the knife, thou wise one.' This is the meaning.  The fork is a symbol for doubt. Throw out the fork means abandon doubt. Delve with the knife, thou wise one.' This is the meaning. The sieve is a symbol for the five hindrances, namely sensual desire, ill will,  sloth and torpor,  restlessness and remorse and doubt. Throw out the sieve means abandon the five hindrances. Delve with the knife, thou wise one. This is the meaning.

​"The tortoise is a symbol for the five aggregates affected by clinging, namely material form, feeling, perception,  formations and the consciousness.  Throw out the tortoise means abandon the five aggregates affected by clinging. Delve with the knife, thou wise one.' This is the meaning.  The axe and block is a symbol for the five cords of sensual pleasure - forms cognizable by the eye that are wished for, desired, agreeable, and likeable, connected with sensual desire, and provocative of lust; sounds cognizable by the ear...odors cognizable by the nose...flavors cognizable by the tongue... tangibles cognizable by the body. Throw out the axe and block means abandon the five cords of sensual pleasure. Delve with the knife, thou wise one. This is the meaning. The piece of meat is a symbol for delight and lust. Throw out the piece of meat means abandon delight and lust. Delve with the knife, thou wise one.' This is the meaning.  The Naga serpent is a symbol for a bhikkhu who has destroyed the taints. Leave the Naga serpent; do not harm the Naga serpent; honor the Naga serpent. This is the meaning." 

That is what the Blessed One said. The venerable Kumara Kassapa was satisfied and delighted in the Blessed One's words. 
In summary, a deva appeared before Venerable Kumara Kassapa and presented him with an obscure riddle, which is unraveled for him by the Buddha. The deva advised Kassapa to learn from the blessed wise one and to be mindful of one's actions, speech and thoughts every moment. He also advised him to abandon ignorance, despair due to anger, doubt, five hindrances and five aggregates affected by clinging so as to become a bhikkhu who has destroyed all taints. 
References: 
1. www.accesstoinsight.org
2. https://suttacentral.net/
3. The long discourses of the Buddha (Bhikkhu Bodhi)