Translated from the Pali
Thus have I heard. At one time the Blessed One was dwelling at Bārāṇasī in the Deer Park at Isipatana. There the Blessed One addressed the bhikkhus of the group of five thus: "Bhikkhus, these two extremes should not be followed by one gone forth (into the homeless life). What two? That which is this pursuit of sensual happiness in sense pleasures, which is low, vulgar, the way of the ordinary person, ignoble, not connected to the goal; and that which is this pursuit of self-mortification, which is painful, ignoble, not connected to the goal. Bhikkhus, without veering towards either of these two extremes, the One Attuned to Reality has awakened to the middle way, which gives rise to vision, which gives rise to knowledge, which leads to peace, to higher knowledge, to full awakening, to Nibbāna.
"And what, bhikkhus, is that middle way awakened to by the One Attuned to Reality which gives rise to vision, which gives rise to knowledge, which leads to peace, to higher knowledge, to full awakening, to Nibbāna? It is just this Noble Eight-factored Path, that is to say, right view, right resolve, right speech, right action, right livelihood, right effort, right mindfulness, right mental unification. This, bhikkhus, is that middle way awakened to by the One Attuned to Reality, which gives rise to vision, which gives rise to knowledge, which leads to peace, to higher knowledge, to full awakening, to Nibbāna.
"Now this, bhikkhus, for the spiritually ennobled ones, is the true reality which is pain: birth is painful, aging is painful, illness is painful, death is painful; sorrow, lamentation, physical pain, unhappiness and distress are painful; union with what is disliked is painful; separation from what is liked is painful; not to get what one wants is painful; in brief, the five bundles of grasping-fuel are painful.
"Now this, bhikkhus, for the spiritually ennobled ones, is the pain-originating true reality. It is this craving which leads to renewed existence, accompanied by delight and attachment, seeking delight now here now there; that is, craving for sense-pleasures, craving for existence, craving for extermination (of what is not liked).
"Now this, bhikkhus, for the spiritually ennobled ones, is the pain-ceasing true reality. It is the remainderless fading away and cessation of that same craving, the giving up and relinquishing of it, freedom from it, non-reliance on it.
"Now this, bhikkhus, for the spiritually ennobled ones, is the true reality which is the way leading to the cessation of pain. It is this Noble Eight-factored Path, that is to say, right view, right resolve, right speech, right action, right livelihood, right effort, right mindfulness, right mental unification.
"'This, for the spiritually ennobled ones, is the true reality of pain': in me, bhikkhus, in regard to things unheard before, there arose vision, knowledge, wisdom, true knowledge, and light.
"Now on this, 'This — for the spiritually ennobled ones, the true reality of pain — is to be fully understood': in me, bhikkhus, in regard to things unheard before, there arose vision, knowledge, wisdom, true knowledge, and light.
"Now on this, 'This — for the spiritually ennobled ones, the true reality of pain — has been fully understood': in me, bhikkhus, in regard to things unheard before, there arose vision, knowledge, wisdom, true knowledge, and light.
"(Likewise,) in me, bhikkhus, in regard to things unheard before, there arose vision, knowledge, wisdom, true knowledge and light, with respect to: 'This, for the spiritually ennobled ones, is the pain-originating true reality,' 'This — for the spiritually ennobled ones, the pain-originating true reality — is to be abandoned,' and 'This — for the spiritually ennobled ones, the pain-originating true reality — has been abandoned.'
"(Likewise,) in me, bhikkhus, in regard to things unheard before, there arose vision, knowledge, wisdom, true knowledge and light, with respect to: 'This, for the spiritually ennobled ones, is the pain-ceasing true reality,' 'This — for the spiritually ennobled ones, the pain-ceasing true reality — is to be personally experienced' and 'This — for the spiritually ennobled ones, the pain-ceasing true reality — has been personally experienced.'
"(Likewise,) in me, bhikkhus, in regard to things unheard before, there arose vision, knowledge, wisdom, true knowledge and light, with respect to: 'This, for the spiritually ennobled ones, is the true reality which is the way leading to the cessation of pain,' 'This — for the spiritually ennobled ones, the true reality which is the way leading to the cessation of pain — is to be developed,' and 'This — for the spiritually ennobled ones, the true reality which is way leading to the cessation of pain — has been developed.'
"So long, bhikkhus, as my knowledge and seeing of these four true realities for the spiritually ennobled ones, as they really are in their three phases (each) and twelve modes (altogether) was not thoroughly purified in this way, then so long, in the world with its devas, māras and brahmās, in this population with its renunciants and brahmans, its devas and humans, I did not claim to be fully awakened to the unsurpassed perfect awakening. But when, bhikkhus, my knowledge and vision of these four true realities for the spiritually ennobled ones, as they really are in their three phases and twelve modes was thoroughly purified in this way, then, in the world with its devas, māras and brahmās, in this population with its renunciants and brahmans, its devas and humans, I claimed to be fully awakened to the unsurpassed perfect awakening. Indeed, knowledge and seeing arose in me: 'Unshakeable is the liberation of my mind; this is my last birth: now there is no more renewed existence.'"
This is what the Blessed One said. Elated, the bhikkhus of the group of five delighted in the Blessed One's statement. And while this explanation was being spoken, there arose in the venerable Koṇḍañña the dust-free, stainless vision of the Basic Pattern: "whatever is patterned with an origination, all that is patterned with a cessation."
And when the Wheel (of Vision) of the Basic Pattern (of things) had been set in motion by the Blessed One, the earth-dwelling devas raised a cry: "At Bārāṇasī, in the Deer Park at Isipatana, the unsurpassed Wheel (of Vision) of the Basic Pattern (of things) has been set in motion by the Blessed One, which cannot be stopped by any renunciant or brahman or māra or brahmā or by anyone in the world." Having heard the cry of the earth-dwelling devas, the devas of the Four Great Kings raised the same cry. Having heard it, the Thirty-three devas took it up, then the Yāma devas, then the Contented devas, then the devas Who Delight in Creating, then the devas With Mastery in the Creations of Others, and then the devas of the brahmā group.
Thus at that moment, at that instant, at that second, the cry spread as far as the brahmā world, and this ten thousandfold world system shook, quaked, and trembled, and an immeasurable glorious radiance appeared in the world, surpassing the divine majesty of the devas.
Then the Blessed One uttered this inspiring utterance: "the honorable Koṇḍañña has indeed understood! The honorable Koṇḍañña has indeed understood! In this way, the venerable Koṇḍañña acquired the name Koṇḍañña Who Has Understood.
Translator's note: The setting: seven weeks after the Buddha's enlightenment/awakening, he goes to five former companions that he had previously practiced extreme asceticism with (Vin i 8-10). After trying asceticism, he had given this up for a more moderate approach based on a healthy body and jhāna (mindful, calm and joyful altered states of consciousness based on samādhi (mental unification)). The following is seen as the first teaching he gave to anyone. In other contexts, the Buddha taught the Four True Realities for the Spiritually Ennobled Ones to people after first giving them a preparatory discourse to ensure they were in the right frame of mind be able to fully benefit from the teaching:
"Then the Blessed One gave the householder Upāli a step-by-step discourse, that is, talk on giving, talk on moral virtue, talk on the heaven worlds; he made known the danger, the inferior nature of and tendency to defilement in sense-pleasures, and the advantage of renouncing them. When the Blessed One knew that the householder Upāli's mind was ready, open, without hindrances, inspired and confident, then he expounded to him the elevated Dhamma-teaching of the buddhas: dukkha, its origination, its cessation, the path." [M i 379-80]
The four true realities taught by the Buddha are not as such things to "believe" but to be open to, see and contemplate, and respond to appropriately: by fully understanding dukkha/pain/the painful, abandoning that which originates it, personally experiencing its cessation, and cultivating the path that leads to this. These four true realities are the four fundamental dimensions of experience, as seen by a spiritually noble person with deep wisdom: the conditioned world, that which originates it, the cessation/transcending of it (the unconditioned, Nibbāna), and the path to this. Indeed, it is by insight into these that a person becomes spiritually ennobled.