釋氏要覽 1.313

1.313

古僧依律制。只有僧祇支（此名覆膊。亦名掩腋衣）此長覆左膊及掩右掖蓋儭三衣故即天竺之儀也。竺道祖魏錄云。魏宮人見僧袒一肘不以為善。乃作偏袒縫於僧祇支上相從因名偏衫（今開脊接領者蓋遺魏制也）。

Ancient monks followed the vinaya's institution of having only the saṃkakṣikā (this means 'shoulder-cover', also called 'underarm-covering garment'); this draped over the left shoulder and covered the right underarm, worn directly beneath the three robes, which was the Indian style. Zhu Daozu's Records of Wei states: 'When the Wei palace attendants saw the monks baring one arm, they thought it improper, and so made a single-shoulder piece sewn onto the saṃkakṣikā; following this, it came to be called the pianshan.' (The present style with a split back and joined collar is a vestige of the Wei institution.)