Buddhavacana in Pali and Sanskrit literally means "the Word of the Buddha". This term generally refers to literary works accepted within a particular Buddhist tradition as being the authentic teaching of the historical Buddha. Many Buddhist traditions recognize certain texts as buddhavacana which are not regarded necessarily as actual words of the historical Buddha but which are nonetheless regarded as doctrinally authentic such as the Theragāthā and Vimalakīrti Nirdeśa Sūtra.
According to Donald Lopez, criteria for determining what should be considered buddhavacana was developed at an early stage, and that the early formulations do not suggest that the Dharma is limited to what was spoken by the historical Buddha. The Mahāsāṃghika and the Mūlasarvāstivāda considered both the Buddha's discourses, as well those of the Buddha's disciples, to be buddhavacana.
A number of different beings such as buddhas, disciples of the buddha, ṛṣis, and devas were considered capable to transmitting buddhavacana. The content of such a discourse was then to be collated with the sūtras, compared with the Vinaya, and evaluated against the nature of the Dharma. These texts may then be certified as true buddhavacana by a buddha, a saṃgha, a small group of elders, or one knowledgeable elder.
Surveying the voluminous corpus of Buddhist texts that originated in India, Ronald Davidson writes that Indian Buddhists were prolific writers of buddhavacana literature, and that was a special quality of Indian Buddhism:
Given the extraordinary extent of material passing at any one time under the rubric of the "word of the Buddha," we might simply pause and acknowledge that Indian Buddhists were extraordinarily facile literateurs. [...] Institutional creativity of this order, at this level, over this length of time, is sheer inspired genius.
In Theravada Buddhism, the standard collection of buddhavacana is the Pali Canon. The oral tradition of the Theravadin recension of Buddhist texts dates back to the time of the Buddha but was not written down until 29 BCE, with continuous revisions up to about 500 CE, taking its present form.
According to Venerable Hsuan Hua from the tradition of Chinese Buddhism, there are five types of beings who may speak the sutras of Buddhism: a buddha, a disciple of a buddha, a deva, a ṛṣi, or an emanation of one of these beings; however, they must first receive certification from a buddha that its contents are true Dharma. Then these sutras may be properly regarded as buddhavacana.
In Tibetan Buddhism, what is considered buddhavacana is collected in the Kangyur. The East Asian and Tibetan Buddhist canons always combined Buddhavacana with other literature in their standard collected editions. However, the general view of what is and is not buddhavacana is broadly similar between East Asian Buddhism and Tibetan Buddhism.