B.G 6.11 and 12
शुचौ देशे प्रतिष्ठाप्य स्थिरमासनमात्मनः। नात्युच्छ्रितं नातिनीचं चैलाजिनकुशोत्तरम् ॥११॥
तत्रैकाग्रं मनः कृत्वा यतचित्तेंद्रियक्रियः। उपविश्यासने युञ्ज्यात् योगमात्मविशुद्धये ॥१२॥
śucau deśe pratiṣṭhāpya sthiramāsanamātmanaḥ। nātyucchritaṁ nātinīcaṁ cailājinakuśottaram ॥11॥
tatraikāgraṁ manaḥ kr̥tvā yatacitteṁdriyakriyaḥ। upaviśyāsane yuñjyāt yogamātmaviśuddhaye ॥12॥
[शुचौ देशे प्रतिष्ठाप्य स्थिरम् आसनमात्मनः। न अति उच्छ्रितं न अति नीचं चैलाजिन कुश उत्तरम्॥ तत्र एकाग्रं मनः कृत्वा यतचित्त इद्रिय क्रियः। उपविश्य आसने युञ्ज्यात् योगम् आत्म विशुद्धये॥
शुचौ (śucau) - In a clean; देशे (deśe) - place; प्रतिष्ठाप्य (pratiṣṭhāpya) - having established; स्थिरम् (sthiram) - steady; आसनम् (āsanam) - seat; आत्मनः (ātmanaḥ) - for oneself; न (na) - not; अति (ati) - too much; उच्छ्रितं (ucchritaṁ) - high; न (na) - not; अति (ati) - too much; नीचं (nīcaṁ) - low; चैलाजिन (cailājina) - made of cloth or deer skin; कुश (kuśa) - of kuśa grass; उत्तरम् (uttaram) - superior. तत्र (tatra) - There; एकाग्रं (ekāgraṁ) - one-pointed; मनः (manaḥ) - mind; कृत्वा (kṛtvā) - having made; यतचित्त (yatacitta) - controlled mind; इद्रिय (indriya) - senses; क्रियः (kriyaḥ) - activities; उपविश्य (upaviśya) - having seated; आसने (āsane) - on the seat; युञ्ज्यात् (yuñjyāt) - one should engage; योगम् (yogam) - the practice of Samadhi-Yoga; आत्म (ātma) - self; विशुद्धये (viśuddhaye) - for purification.]
In a clean place, having established a steady seat for oneself, neither too high nor too low, made of cloth or deerskin, and kuśa grass; there, having made the mind one-pointed and controlling the activities of the senses, one should sit, engaging in the practice of Samādhi-Yoga for self-purification.
Gīta Bhāshya 6.11 and 12
'yogam yuñjyat' - practice of Samādhi-Yoga, i.e. Yoga to attain the equanimous state.
योगं स्माधियोगं युञ्ज्यत्।
yogaṁ smādhiyogaṁ yuñjyat।
[योगं (yogam) - Yoga; स्माधियोगं (smādhiyogam) - the yoga of meditation; युञ्ज्यत् (yuñjyat) - one should practice.]
The word 'yogam yuñjyat' refers to the practice of Samādhi-Yoga, i.e. Yoga to attain equanimous state.