Patanjali Yoga Sutra 2.49

Sanskrit Sutra

तस्मिन् सति श्वासप्रश्वासयोर्गतिविच्छेदः प्राणायामः॥४९॥

Swami Vivekananda's translation

Controlling the motion of the exhalation and the inhalation follows after this.

Chapter link: Yoga Sutra Chapter 2