The book of Lamentations gives us a glimpse of who Jesus is in the Old Testament (O.T).
The book of Lamentations has 5 chapters, each with 22 verses except Chapter 3 that has 66 verses and the statement Great is thy faithfulness is in the epicenter of the book (Lamentations 3:23).
Rev 19:11 records the name of Jesus will be Faithful and True;
Faithfulness is the epicenter of Jesus’ character.
We can read in Lamentations, Great is His Faithfulness, because GREAT is THE FAITHFUL ONE. We can sing Great is thy Faithfulness, by replacing faithfulness with Faithful One. And what is even more is that even if we are faithless, He remains faithful (2 Tim 2:11-14)
In Lamentations, Jesus is the Faithful One, the ever Faithful one.