Original Text Vidur Niti - Mahabharat - Udyog Parva (33-41) in Sanskrit
Vidura was half-brother of King Dhritaraashtra and Pandu.
King Vichitraveerya had two wives, Ambika and Ambalika. However before any child was concieved the king died due to a tragedy. Vichitravirya's mother, Satyavati, wanted the royal line to continue. Ambika gave birth to Dhritaraashtra and Ambalika to Pandu fathered by Vyasa at the behest of his mother Satyvati. Vidura was born of a handmaiden of Ambika by Sage Vyasa. He was therefore half-brother to both Dhritaraashtra and Pandu.
Vidura is the incarnation of Yama, the very embodiment of dharma. He took birth as a human being owing to a curse by sage Mandavya. Yama had imposed punishment far in excess of the sin committed by the sage unwittingly as a boy. Hence the curse on Yama.
Vidura was raised and educated by Bhishma along with his half-brothers. He was known for speaking the truth and for his intelligence and depth of knowledge. He served his brothers as a minister. He was a friend of the Pandavas and a great devotee of Krishna. In spite of being a royal minister he led a simple life.
Vidura Neeti, mainly on the science of politics, is narrated in the form of a conversation between Vidura and King Dhritraashtra in the great epic Mahabharata. It is often cited as the precursor of the more famous Chanakya Neeti.