Yoga Sutra 2.53: And, the mind attains the ability for Dharana, concentration, with Pranayama.

53rd Sutra Chapter 2 And, the mind attains the ability to concentrate, to focus its attention. Pranayama is not only an instrument to steady and purify the mind to experience the prakash of the buddhi, the dawn of wisdom, as detailed in the last Sutra, but also the gateway to concentration, Dharana. Dharana is the sixth limb of AshtangaYoga, the eight limbed Yoga; but Maharishi Patanjali introduces it before the fifth limb, Pratyahara, withdrawal of the senses. Maybe so because Dharana is the ability of fixing the mind on something external, as well as internal. After the Pranayama practice has steadied the wandering mind, the power of concentration can be developed. In Dharana, we have only one Vriiti or Wave in the mind lake. The mind assumes the form of only one object. All other operations of the mind are suspended or stopped. Dharana can be done only if we are free from the distractions of the mind. The implication here is clear that the sadhaka who had to struggle initially to cultivate a yogic way of life by Tapas, self-discipline and Swadhyaya, self-study, now finds his efforts transformed into a natural zeal to proceed in his sadhana. ——————- धारणासु च योग्यता मनसः॥२.५३॥ dhāraṇāsu ca yogyatā manasaḥ ॥2.53॥ • dharanasu - concentration • cha - and • yogyata - capability • manasah - of the mind. The mind acquires fitness for Dharana. धारणासु च योग्यता मनसः॥२.५३॥ • च - और • मनस: - मन को • धारणासु - कहीं भी एकाग्र करने की • योग्यता - काबलियत या सामर्थ्य बढ़ जाता है । और प्राणायाम के करने से मन को कहीं पर भी एकाग्र करने यालगाने का सामर्थ्य बढ़ जाता है ।