Baizhang Huaihai (Chinese: 百丈懷海; pinyin: Bǎizhàng Huáihái; Wade-Giles: Pai-chang Huai-hai; Japanese: Hyakujō Ekai) (720–814) was a Chinese Zen master during the Tang Dynasty. He was a dharma heir of Mazu Daoyi (Wade-Giles: Ma-tsu Tao-i). Baizhang's students included Huangbo, Linji and Puhua.
According to traditional Chan/Zen accounts, Baizhang established an early set of rules for Chan (Chinese Zen) monastic discipline, the Pure Rules of Baizhang (Chinese: 百丈清規; pinyin: Bǎizhàng qīngguī; Wade–Giles: Pai-chang ch'ing-kuei),Korean: 백장청규) It was practiced in Ta-chih shou-sheng ch'an-ssu (Jp. Daichijusho-zenji), founded by Baizhang. This monastery contained a monks hall, an innovation which became typical for Chán:
During periods of ascetic practice the monks would sleep on the same straw mat on which they sat in meditation and on which, according to defined ritual, they took their meals. Both the lifestyle Pai-chang spelled out as well as the architectural form of his monastery became models for later Zen monasteries".
Some believe these rules developed much later in Chan history, and are agreed by the monks Taixu and Hsu Yun.
As the Zen monks farmed, it helped them to survive the Great Anti-Buddhist Persecution more than other sects which relied more on donations. These rules are still used today in many Zen monasteries. From this text comes the well-known saying "A day without work is a day without food" (一日不做一日不食 "One day not work, one day not eat").
Baizhang's teachings and sayings have been translated by Thomas Cleary in Sayings and Doings of Pai-Chang.
The Zen Teachings of Instaneous Awakening has been attributed by some to Baizhang Huaihai, but was in fact a work by his dharma brother, Ta-chu Hui-hai
The Wild fox koan is attributed to Baizhang.
- Dumoulin, Heinrich (2005-A), Zen Buddhism: A History. Volume 1: India and China, World Wisdom Books, ISBN 9780941532891