The one-legged pigeon pose is an elegant pose that works on stretching the front outer hip and the back quads. There are many variations of the Pigeon: seated version, forward bend version (as seen in the pictures on this page), twisting version, mermaid (which is a backbend), and the one legged King Pigeon (a backbend and shoulder opener). The backbend versions stretch the psoas a bit more that the rest. Below are the instructions for this forward bend version STEP-BY-STEP
Either from hands and knees or Downward Dog, with the pelvic floor and the lower belly in and up, exhale to step the right leg forward, foot dorsi-flexed (toes drawn back towards the shin) placing the right knee down behind the right wrist with the right foot towards the left hip. If this is not comfortable, try bringing the right knee more towards the centre, between the two hands, and the right foot back towards the right sitbone.
Lower the left leg onto the mat, and stretch it straight back (look back and make sure it is going straight back). You can release the top of the left foot into the mat or keep the toes tucked, which can help to square the hips to the front of the mat.
Keep the hips facing forward and the weight moving down into the tailbone and sitbones. Don't sink to one hip or the other or bear down on the front knee. If it's not possible to stay centred with the weight moving back towards the tailbone and both sitbones equally, please work on the seated version.
Keep the tailbone reaching down and the belly engaged, inhale to lengthen the spine. Exhale to slowly lower onto the elbows (as in the small picture). If this is enough, please stay and breathe. If you can release further, come on down and maybe rest your head on your fists or forearms. If you can get your head to the floor, go ahead, mindfully and with respect for the hips and knee.
Once in your pose, breathe in and out of the belly to release tension from the hips. The floor is your support. The core can be relaxed here. Stay for at least 1 minute. It takes time for the muscles in the hips to release! Remember to keep your shoulders away from you ears!
ENJOY and don't forget to do the other side. I always hold the tighter side longer than the other one.