The Yamas are codified as "the restraints" in numerous scriptures including the Shandilya and Varuha Upanishads, Hatha Yoga Pradipika by Gorakshanatha, the Tirumantiram of Tirumular and the Yoga Sutras of Patanjali. All the above texts list ten yamas, with the exception of Patanjali's work, which lists only five. They comprise the "shall-nots" in our dealings with the external world.
The ten traditional yamas are:
Ahimsa: abstinence from injury, harmlessness, the not causing of pain to any living creature in thought, word, or deed at any time. This is the "main" Yama. The other nine are there in support of its accomplishment.
Satya: truthfulness, word and thought in conformity with the facts.
Asteya: non-stealing, non-coveting, non-entering into debt.
Brahmacharya: divine conduct, continence, celibate when single, faithful when married.
Kshama: patience, releasing time, functioning in the now.
Dhriti: steadfastness, overcoming non-perseverance, fear, and indecision; seeing each task through to completion.
Daya: compassion; conquering callous, cruel and insensitive feelings toward all beings.
Arjava: honesty, straightforwardness, renouncing deception and wrongdoing.
Mitahara: moderate appetite, neither eating too much nor to little; nor consuming meat, fish, shellfish, fowl or eggs.
Shaucha: purity, avoidance of impurity in body, mind and speech. (Note: Patanjali's Yoga Sutras list Shaucha as the first of the Niyamas.)
The spirits of the dead, on being judged by Yama, are supposed to either pass through a term of enjoyment in a region midway between the earth and the heaven of the gods, or to undergo their measure of punishment in Naraka (or Jigoku), the nether world, situated somewhere in the southern region.
Yama is also the lord of justice and is sometimes referred to as Dharma, in reference to his unswerving dedication to maintaining order and adherence to harmony.
Yama was revered in Tibet as a guardian of spiritual practice.