The book "O Worship the King: Hymns of Assurance and Praise to Encourage Your Heart" is a collection of hymns designed to uplift and encourage readers' hearts. Published by Crossway in 2000, this hardcover book features hymns by well-known authors such as Joni Eareckson Tada, John Macarthur, Bobbie Wolgemuth, and Robert Wolgemuth. With 126 pages, this book is part of the Great Hymns of Our Faith series and is perfect for those looking to sing and praise through the power of music and faith.