Hathayoga 1-48

नासाग्रे विन्यसेद्राजद्-अन्त-मूले तु जिह्वया ।
उत्तम्भ्य चिबुकं वक्षस्युत्थाप्य् पवनं शनैः ॥ ४८॥

Nāsāghre vinyasedrājadantamūle tu jihvayā Uttambhya chibukam vakshasyutthāpy pavanam śanaih

Gaze on the tip of the nose, keeping the tongue pressed against the root of the teeth of the upper jaw, and the chin against the chest, and raise the air up slowly, i.e., pull the apânavâyû gently upwards.