He is the Speaker in the Burning Bush on Sinai

This beautiful and dramatic explanation by the Guardian clearly tells us that Baha'u'llah is the essence, the culmination and the consummation of all the revelations of the past. He is not just another prophet. He is the Lord of Hosts, the incarnation of the Holy Spirit, and the Inaugurator of the Day of God. Doesn't he state in the medium obligatory prayer that He is the Speaker in the Burning Bush on Sinai?

https://bahai-library.com/wttp/PDF/A%20Glimpse%20of%20Glory.pdf