Ashtanga Yoga is the yoga of Patanjali as “Ashtanga” means “eight limbs” or “stages” found described in his Sutras.
One of Patanjali’s sutras orders a total devotion to God as part of the practice that helps to reach Samadhi (the last limb): “Isvara Pranidhana“. It is the final Niyama. Niyama is the 2nd stage of Yoga and means “rules” or “restrictions”. Isvara is the name of God in Sanskrit and Pranidhana means “attention to, love for, surrender to, faith in,” or “reunion with” “Attentiveness” and “Surrender”.
Here is a great article reflecting on the notion of Isvara Pranidhana, its relation with our daily yoga practice and its effectiveness in creating concentration on what is essential for us, written by David Garrigues.
Ashtanga Yoga Beirut 