One of the four Vedas, specifically dealing with the mantras said while performing each step of a Yagna.
The Yajurveda (Sanskrit: यजुर्वेदः yajurveda, a tatpurusa compound of yajus "sacrificial formula" and veda "knowledge") is one of the four canonical texts of Hinduism, the Vedas. Estimated to have been mostly composed c. 1200–1000 BCE (see below), the Yajurveda Samhita, or "compilation", contains the liturgy (mantras) needed to perform the sacrifices of the historical Vedic religion, and the added Brahmana and Śrautasutra add information on the interpretation and on the details of their performance.