Wikipedia: (Sanskrit: नियम niyama, "restraint", "observance", "rule", "restriction", "certainly", "necessarily" generally denotes a duty or obligation adopted by a spiritual aspirant (or community of same), or prescribed by a guru or by scripture (notably, the niyamas of raja yoga).
Ten niyamas are codified as “the obligations” or "inner observances" in numerous scriptures including the Shandilya and Varaha Upanishads, the Hatha Yoga Pradipika by Gorakshanatha, and the Tirumantiram of Tirumular. Patañjali lists only five niyamas in his Yoga Sūtras.
10 Traditional Niyamas: Hiri, Santosha, Dana, Astikya, Ishvarapujana, Siddhanta Shravana, Mati, Vrata, Japa and Tapas.
5 Niyamas of Patanjali: Saucha, Santosha, Tapas, Svadhyaya and Ishvara Pranidhana.