Yoga Sutras 4.28
Patanjali, explained by Swami Vivekananda
प्रसंख्यानेऽप्यकुसीदस्य सर्वथा विवेकख्यातेर्धर्ममेघः समाधिः ॥
prasaṃkhyāne'pyakusīdasya sarvathā vivekakhyāterdharmameghaḥ samādhiḥ
Even when arriving at the right discriminating knowledge of the essences, he who gives up the fruits, unto him comes, as the result of perfect discrimination, the Samadhi called the cloud of virtue.
In plain words: Even after gaining clear understanding, the yogi who gives up the rewards and special powers reaches a deep meditation called Dharma-megha, the cloud of virtue. The teacher says it brings peace, calm and purity.
Swami Vivekananda explains
When the Yogi has attained to this discrimination, all the powers mentioned in the last chapter come to him, but the true Yogi rejects them all. Unto him comes a peculiar knowledge, a particular light, called the Dharma-megha, the cloud of virtue. All the great prophets of the world whom history has recorded had this. They had found the whole foundation of knowledge within themselves. Truth to them had become real. Peace and calmness, and perfect purity became their own nature, after they had given up the vanities of powers.