Mini-workshop Yamas & Niyamas #1: Ahimsa and Saucha
Probably the most important Yama is the first: Ahimsa. See the symbol of Ahimsa (meaning stop) embodying the qualities of compassion and kindness, stopping all thought or action of harm or violence. The mantra used is Lokah Samastah Sukhino Bhavantu = "May all beings be free and happy and may my thoughts and actions contribute to that freedom for all." In Virabhadrasana I and II, you can hold while contemplating Padma Mudra and mantra given.
The first of Niyamas, Saucha represents Purity, both of body and mind, some even interpreting as to what they consume for food. Mantra: Om Aim Hridayam Namaha.