Bhagavad Gita 5.27

स्पर्शान्कृत्वा बहिर्बाह्यन्श्चक्षुश्चैवन्तरे भ्रुवो: |
प्राणापानौ समौ कृत्वा नासाभ्यन्तरचारिणौ

Translation

Shutting out all thoughts of external enjoyment, with the gaze fixed on the space between the eye-brows, equalizing the flow of the incoming and outgoing breath in the nostrils