Shri Ramanujacharya's Bhagavad Gita Bhashya (Commentary) - BG 6.13

समं कायशिरोग्रीवं धारयन्नचलं स्थिरः
संप्रेक्ष्य नासिकाग्रं स्वं दिशश्चानवलोकयन्

samaṃ kāyaśirogrīvaṃ dhārayannacalaṃ sthiraḥ
saṃprekṣya nāsikāgraṃ svaṃ diśaścānavalokayan

Holding the trunk, head and neck erect, motionless and steady, gazing at the tip of the nose, and looking not in any direction;