The book of Mark has 28 direct Old Testament quotations.
There are 28 writers of the Old Testament (Amos, Daniel, David, Davidic priests, Esther, Ezekiel, Ezra, Habakkuk, Haggai, Hezekiah, Hosea, Isaiah, Jeremiah, Job, Joel, Jonah, Joshua, Malachi, Micah, Mordecai, Moses, Nahum, Nehemiah, Obadiah, Ruth, Samuel, Solomon, Zechariah, Zephaniah).
The phrase ‘the Lamb,” used to refer to Jesus Christ as the Lamb that takes away the sins of the world, occurs 28 times. The word “Hallelujah” also appears 28 times.
Of the top ten occurring names in the entirety of God’s word, the name David appears in 28 Books.
The book of Acts, with its 28 chapters, is the longest book in the New Testament.
Jehu, a mostly bad king, ruled over Israel for 28 years (2Kings 10:36).