Sarnath (Isipatana)

After the Buddha attained enlightenment at Bodh Gayā, he decided to teach the liberating truths he had discovered. As his two former teachers, Alara Kālāma and Uddaka Rāmaputta, had both died, he decided to seek out his five former companions and present his Dhamma to them. With his supernatural powers he came to know that they were staying in the Deep Park (Migadaya) at Isipatana, now called Sārnāth, near Vārānasi, and so he set out to find them. These five companions had abandoned him after he gave up his austerities, accusing him of ‘reverting to the life of luxury.’ As the Buddha approached the Deer Park and the five ascetics saw him, they decided they would not stand up to greet him.

But as soon as he came closer, they were entranced by the utterly peaceful expression on his face, and one by one they spontaneously rose from their seats. At first they refused to believe that he was as he claimed—enlightened. ‘Have I ever spoken to you in this way before?’ he asked, and they admitted that he had not, and so they decided that they would listen to him. And thus the good Dhamma came to be proclaimed to the world for the first time in a discourse, now called the Dhammacakkappavattana Sutta.
Soon afterwards, he taught his second discourse, the Anattalakhana Sutta after which the five companions Kondañña, Bhaddiya, Vappa, Mahānāma and Assaji, all became enlightened. (Excerpt from Middle Land, Middle Way, A Pilgrim's Guide to the Buddha's India by Ven. Dhammika).

Excerpt Chapter 6 from The Buddha and his Teachings by Ven. Nārada Mahāthera (Pariyatti Edition):

The First Discourse of the Buddha
Dhammacakka is the name given to this first discourse of the Buddha. It is frequently represented as meaning “the kingdom of truth,” “the kingdom of righteousness,” or “the wheel of truth.” According to the commentators dhamma here means wisdom or knowledge, and cakka means founding or establishment.
Dhammacakka therefore means the founding or establishment of wisdom. Dhammacakkappavattana means The Exposition of the Establishment of Wisdom. Dhamma may also be interpreted as truth, and cakka as wheel. Dhammacakkappavattana would therefore mean The Turning or The Establishment of the Wheel of Truth.

In this most important discourse the Buddha expounds the Middle Path which he himself discovered and which forms the essence of his new teaching. He opened the discourse by exhorting the five monks who believed in strict asceticism to avoid the extremes of self-indulgence and self-mortification as both do not lead to perfect peace and enlightenment. The former retards one’s spiritual progress, the latter weakens one’s intellect.

Excerpt from the Dhammacakkapavattanasutta, translated by Glenn Wallis (as in the Pāli Reader Buddhavacana):

“Not tending towards either of these extremes, a Tathāgata – person who has come to know reality – has completely awakened to the middle way. The middle way engenders insight and understanding, and leads to calmness, to direct knowledge, to full awakening, to unbinding. So what is that middle way completely awakened to by a Tathāgata? It is precisely this preeminent eight-component course; namely, sound view, sound inclination, sound speech, sound action, sound livelihood, sound effort, sound awareness, and sound concentration. This is the middle way, realized by a Tathāgata, which gives rise to vision and knowledge, and leads to calmness, to direct knowledge, to full awakening, to unbinding.

“Now, this is unease. It is a preeminent reality. Birth is unsettling, aging is unsettling, illness is unsettling, death is unsettling, association with what is displeasing is unsettling, separation from what is pleasing is unsettling, not getting what is wanted is unsettling. In short, the five existential functions subject to grasping are unsettling. “This is the origination of unease. It is a preeminent reality. It is this craving that leads to further being, accompanied by passion and delight, seeking pleasure here and there. It is, namely, craving for sensual pleasures, craving for being, and craving for non-being.

Excerpt Dhammapada; Verses & Stories:

While residing at the Isipatana wood, the Buddha uttered Verses (219) and (220) of this book, with reference to Nandiya. Nandiya was a rich man from Bārāṇasī. After listening to the Buddha’s discourse on the benefits of building monasteries for bhikkhus, Nandiya built the Mahāvihāra monastery at Isipatana. The building was pinnacled and fully furnished. As soon as the monastery was offered to the Buddha, a mansion came up for Nandiya at the Tāvatiṃsa deva world.

One day, when Thera Mahā Moggallāna visited the Tāvatiṃsa deva world he saw the mansion which was meant for the donor of the Mahāvihāra monastery at Isipatana. On his return from the Tāvatiṃsa deva world, Thera Mahā Moggallāna asked the Buddha, “Venerable Sir! For those who perform meritorious deeds, do they have mansions and other riches prepared in the deva world even while they are still living in this world?” To him the Buddha said, “My son, why do you ask? Have you not yourself seen the mansion and riches waiting for Nandiya in the Tāvatiṃsa deva world? The devas await the coming of the good and generous ones, as relatives await the return cf one who is long absent. When the good ones die, they are welcomed joyously to the abode of the devas.” Then the Buddha spoke in verse as follows: