Book 7 Chapter 35 Srimad Deva Bhagavatam - Parvati teaches Asanas for Bhakti Yoga

After Shakti had taken the form of a goddess, Parvati, She was asked what Asanas were best for Bhakti Yoga? Sitting with ease, was Her answer. Padmasan, Swastikasan, Bhradrasan, Vajrasan, and Virasan were recommended. Padmasan requires crossing the legs and placing the feet on the opposite thighs (right foot on left thigh, left food on right thigh), and catching the toes with the fingers after bringing the arms around the back (right toes in left hand, left toes in right hand), while sitting with ease. If ease is better achieved by putting the hands crossed on the thighs, that is to be done. Swastikasan is practiced by tucking the feet into the knees, onto the knees, or under the knees, and sitting with ease. Bhadrasan, sometimes known as "butterfly" requires sitting with the heels near to the anus and genitals, placing the two hands around the feet, then sitting with ease. Vajrasan is accomplished by placing the feet on the two thighs, and placing the fingers below the thighs to cushion them, then sitting with ease. Virasan consists of sitting on the buttox, and bending the knees back to bring the feet against the sides of the buttox, then sitting with ease.