In the book of ________________, the prophet sees God seated on His throne while the seraphim surround Him singing, "Holy, Holy, Holy..."

The correct answer is found in the book of Isaiah, which details a profound vision experienced by the prophet Isaiah. In Isaiah 6, he describes being transported into the heavenly realm, where he sees the Lord seated on a lofty throne, surrounded by seraphim. These celestial beings proclaim the holiness of God with the words "Holy, Holy, Holy is the Lord of hosts; the whole earth is full of His glory." This scene underscores God's majesty and the seriousness of His holiness, setting the tone for Isaiah's subsequent prophetic ministry. It emphasizes the significance of divine revelation and the calling that Isaiah receives in this moment of worship and awe.