The fourth, the Sanyasi (one who has renounced the world), being established in Brahma, attains immortality (emancipation). Members of all the stages but especially those of the fourth (Sanyasa) desire to know God, the Lord of all Creatures, by means of study, i.e. the teaching of and the listening of the Vedas and by means of acting according to their teachings. A man becomes a muni by knowing God by means of observing Brahmacharya, doing austerities, performing Dharma, faith, intense love, the yajna, imperishable knowledge and performance of virtuous deeds.

The Sanyasis renounce the world on account of their desire to see (realize) God – the most beautiful (lit. worthy to be seen). The excellent Brahmanas, who know God, are free from all doubts, possessed of perfect wisdom, dispellers of the doubts of others, and learned and desire to know God, but, they have no desire for a householder’s life and children.

With beaming faces they say, “What should we do with children (i.e. we have nothing to do with them, the object of our desire is this most beautiful God.)” and thus renouncing the desire to beget children, the desire and efforts for gaining material wealth, the desire for renown, fame and honor and aversion from notoriety in the world, they [live on alms i.e. enter the stage of renunciation.] For, a man who possesses

the desire to beget children, has a desire for wealth, and he who has the desire for worldly fame and honor has the two other desires also viz., those of having children and acquiring wealth. But one who has the desire to attain emancipation and God is free from these three desires.

No riches of the world can equal the riches of the bliss of attaining God. One, who is established in God, no more desires the other honors of the world. He is compassionate to all men and renders all men happy by his true preaching. The only object, he sets his heart upon, is universal benevolence and the propagation of truth.

Chhandogya II. 23.2:Shat. XIV. 7. 2. 

The Sanyasi, having fully ascertained all this and performed the Prajapatya yajna in honor of God, burns his sacred thread and the lock of hair, and with mind accustomed to deep thought and meditation enters the stage of renunciation. But those persons only are entitled to become Sanyasis who are men of deep and perfect knowledge and learning, who are free from attachment and aversion, and whose thoughts are always turned towards the good of al mankind and not those who are men of shallow learning and knowledge.

The Agnihotra of the sanyasis is the burning (i.e. the control) of their in-breathings and out-breathings, the turning away of the senses and the mind from sins and the performance of the true Dharma. The agnihotra of the sanyasis is not that the performance of which is enjoined upon the members of the other threeashramas, nor is it devoid of all activity.

True preaching is the Brahmayajna of the Sanyasis, the worship of God their Devayajna, the honoring of the wise their Pitriyajna, the gift of knowledge to the ignorant, compassion and non-injury to all beings, their Bhutayajna; 

wandering about for the purpose of doing good to all mankind, free from pride, honoring all men by the preaching of truth to them, their Atithiyajna. Thus the five great duties of the Sanyasis consist in true knowledge and he performance of Dharma. But the worship the supreme Brahma, who is one without a second, and possessed of such attributes as almightiness etc. and the following of the true Dharma are common to all the ashramas.

Since man obtains those desires and those places which he desires with a pure mind (the inner sense), one desirous of glory should always respect and honor the sanyasis who know God. By their company and social intercourse with them and by honoring them alone can man obtain the worlds full of bliss and the objects of his desire.

No one should show respect to the preachers of falsehood, those who are devoted to their own self-interest (the self-seeking) and he hypocrites, for, to show respect to them ins useless and its fruit is misery and suffering. Mundak, III, 1.10.