Wisdom

In the Revealing the Profound Secrets Sutra the Buddha tells World Voice Perceiver Bodhisattva:

There are three kinds of wisdom. The first is the wisdom related to conventional truth. The second is the wisdom related to the ultimate truth. The third is wisdom related to the benefit of sentient beings.

T676, 16.705c23-705c24

In the Smaller Prajna Sutra (aka the Sutra of the Perfection of Wisdom in Eight Thousand Lines), the Buddha states that it is the perfection of wisdom that controls and guides the first five.

[The bodhisattva] courses in all the six perfections. But it is the perfection of wisdom that controls the bodhisattva when he gives generously, or guards morality, or perfects himself in patience, or exerts himself energetically, or enters meditative absorption, or has insight into phenomena. One cannot get at a distinction or difference between the six perfections – all of them are upheld by skillful means, dedicated to the perfection of wisdom, dedicated to all-knowledge.

(The Perfection of Wisdom in Eight Thousand Lines & Its Verse Summary, translated by Edward Conze, p. 119, adapted)

Further on in that same sutra the Buddha says:

Furthermore, a bodhisattva who courses in the perfection of wisdom gives a gift that is threefold pure; with his attention centered on the knowledge of all modes, he dedicates to perfect and complete awakening that gift which he gives, after he has made that wholesome root common to all beings. This is the perfection of giving of a bodhisattva who courses in the perfection of wisdom. Similarly should one understand the perfection of morality, patience, energy, and meditation of a bodhisattva who courses in perfect wisdom. With regard to all perfections, and to all dharmas, he sets up the notion that they are an illusion, a dream, a reflected image, an echo, a reflection, a magical creation; with his attention centered on all-knowledge, he dedicates to perfect and complete awakening that wholesome root, after he has made it common to all beings. It is thus that a bodhisattva who courses in perfect wisdom fulfills the perfection of wisdom. A bodhisattva is then called “armed with the great armor.” It is thus that a bodhisattva, having stood firm in every single perfection, fulfills all the perfections.

(Ibid, pp. 130-131, adapted)

The “gift that is threefold pure” is explained by the monk Subhuti in the Larger Prajna Sutra in response to the question of Shariputra as to how the perfection of generosity is different from ordinary worldly generosity that is not informed by the perfection of wisdom:

The supramundane perfection of giving, on the other hand, consists in the threefold purity. What is the threefold purity? Here a bodhisattva gives a gift, and he does not apprehend a self, a recipient, or a gift; also no reward of giving. He surrenders that gift to all beings but does not apprehend those beings, or himself either. And, though he dedicates that gift to supreme awakening, he does not apprehend any awakening.

(The Large Sutra on Perfect Wisdom, translated by Edward Conze, p. 199, adapted)

In the Awakening of Faith in the Mahayana, there is the following exchange regarding the knowledge of the whole and the particulars (or “omniscience” in some translations) that is another way of speaking about the perfect wisdom of the buddhas.

The entire realm of objects is originally the One Mind, which is free of conceptual thought. Because sentient beings have false views regarding the objective realm, their minds are limited. Because they falsely give rise to conceptual thoughts that are not in accord with the Dharma-nature, they are unable to come to any resolutions. [However], the buddhas and tathagatas are free from views and conceptualizing so there is nowhere their [minds] do not reach. Because their minds are true, they are not other than the nature of all dharmas. They naturally reveal and illuminate all false dharmas. By using their great knowledge and infinite skillful means, in accordance with what various sentient beings would be able to understand, they disclose and elucidate the meaning of all kinds of dharmas. Therefore [what they have attained] is called the knowledge of the whole and the particulars.

T1666, 9.581b21-581b27

The Tiantai school teaches that there are three kinds of knowledge. The first is the knowledge of the whole, which corresponds to the wisdom eye achieved by arhats and privately-awakened ones, and bodhisattvas. This is the knowledge that all things are empty of any substantial, independent, unchanging existence. The second is the knowledge of the particulars of the path, which corresponds to the  dharma eye (attained by advanced bodhisattvas). This is knowledge of the causality of provisional existences, especially of the causes and conditions related to the alleviation of suffering and the skillful means that will lead sentient beings to liberation. The third is the knowledge of the whole and the particulars, which corresponds to the buddha eye.  This is knowledge of the supreme meaning and the middle way that overcomes fundamental ignorance and integrates the first two kinds of knowledge in the threefold truth of emptiness, provisionality, and the middle. 

In the Bodhicharyavatara (Introduction to the Practice of Awakening) by the Indian Mahayana monk Shantidva (c. 685 - c. 763), the following is said about the importance of the perfection of wisdom:

1. It is for the sake of wisdom that the Sage taught this entire collection of preparations. Therefore, in the desire to put an end to suffering, one should develop wisdom

The Bodhicaryavatara 9.1 as translated by Kate Crosby and Andrew Skilton (adapted).

Further on, the following statement from the Bodhicaryavatara can serve as a succinct way of explaining how the perfection of wisdom leads to away from anxiety about being and non-being and allows for peace of mind:  

When neither an inherently existent entity (being) nor the non-existence of an entity (non-being) preoccupies the mind, since there is no other alternative, having nothing more to grasp, the mind becomes tranquil. 

Ibid, 9.34 (adapted)

Among many examples, here is a story in which the bodhisattva who becomes Shakyamuni displayed the perfection of wisdom:

In a previous life, Shakyamuni Buddha was Jotipala, the son of the steward of a king. When his father died, he succeeded his father as the steward. He was so proficient that he became known as Mahagovinda (the “great steward”). Mahagovinda was friends with Prince Renu and six other nobles. When the king died, Mahagovinda divided the land into seven portions between King Renu and their six friends. Mahagovinda continued to manage all these lands for them as he had done for the late king. He also was the teacher to seven brahmins and their seven hundred pupils. When it became rumored that Mahagovinda could meet with Brahma face-to-face, Mahagovinda went on retreat to cultivate the contemplation of boundless compassion until he actually could meet Brahma face-to-face. At the end of his retreat, the Brahma Sanankumara appeared to him and taught him that to be reborn in the Brahma heavens one should renounce the home life, overcome greed and hatred, and cultivate compassion. Mahagovinda then shaved off his hair, donned yellow robes, and renounced his home life. He was followed by his family, King Renu, the six nobles, their families, the seven brahmins, and their pupils. All of them wandered from town to town, and cultivated the four divine abodes: loving-kindness, compassion, sympathetic joy, and equanimity. At their end of their lives, Mahagovinda and those who had mastered his teachings were reborn in the Brahma heavens, while those who had only partially mastered them were reborn in the various lower heavens. 

This story is told in the Mahagovinda-sutta, which is the nineteenth discourse in the Long Discourses of the Buddha.

The story of Govinda is briefly referred to in the Great Perfection of Wisdom Treatise wherein it is explained in which lifetimes the bodhisattva who would become Shakyamuni Buddha fulfilled each of the six perfections. 

A version of this story is also told The Three Jewels: A Study and Translation of Minamoto Tamenori's Sanboe.