What is joined to speech and mind, let the wise one separate from that with the knowledge of the Ātman. The knowledge of the Ātman in the great, he should establish it in the tranquil mind.

Here the process of viveka (discrimination) is described: separating the real from the illusory. The prājña (wise one) uses the knowledge of the Ātman to disidentify from vāk (speech/word) and manas (mind). Then, he must establish that knowledge in śānti (tranquility). This is exactly the process of rāja-yoga: first pratyāhāra (withdrawal of senses), then dhāraṇā (concentration), and finally samādhi (absorption).