Are you asking what book in the Bible sought to abolish slavery? Historically, the Catholic church was in charge of how the Bible was interpreted, and it interpreted it as subservient to church tradition, eg, whatever the church had established as true was seen as the standard for interpretation. If the church was ok with slavery, then the bible was interpreted defend it. The Reformation put an end to that, but didn't solve the problem right away. The practice of using the Bible to justify the current cultural conditions is practiced by many, even today, but the Historical Grammatical hermeneutic has gradually become the standard by which theologians interpret. It essentially seeks to understand the culture, time period, and historical knowledge available about the writer, hearers, and readers of the text as it was written, the same way historical documents are treated. Care is taken not to read into the text, but to let the text speak in the manner in which the author intended for his audience.
It was this new way of looking into the scriptures that fueled the Second Great Awakening and gave rise to the abolitionists, who were at the forefront of getting rid of slavery in America. It was the recognition that all men are created equal and endowed by their creator with unalienable rights that led people to start questioning the context of their own culture. Perhaps when Paul stated in the book of Galatians, "28 There is neither Jew nor Gentile, neither slave nor free, nor is there male and female, for you are all one in Christ Jesus." that people began realize that they were no better than other people of different color or cultural backgrounds. I don't know when it clicked, but it did and though some christians were still caught up in defending slavery, many others were at the front-lines fighting and dying to get rid of it. Either way Christians have moved on, and "some" Islamic groups are still stuck in the past, buying and selling slaves as is justified by their teachers of the faith.