Patanajali YogaSutra: 2.29
यमनियमासनप्राणायामप्रत्याहारधारणाध्यानसमाधयोऽष्टावङ्गानि ॥ २.२९॥
Yama niyama asana pranayama pratyhara dharana dhyana samadhayo astavangani ||
The eight limbs of yoga are yama (Universal Observances), niyama (Self disciplinary observances), asana (physical yoga postures), pranayama (breathing exercises-control), pratyahara (withdrawal of the senses), dharana (concentration), dhyana (meditation) and samadhi (Experiencing Oneness with the Supreme)