Deuteronomy 16:12 You shall remember that you were a slave in Egypt.
The Lord commanded the Israelites to remember their bondage during a time of celebration at the end of the harvest season. As Israel finished taking the produce from the land, God commanded them to offer a sacrifice and when they offer it, they are to remember the fruitlessness of their slavery in conjunction with the fruit that they just took in.
Why does the Lord call us to remember our time of slavery? It is because, in the processing of looking back, we see the devastation of being a slave to sin and the delight of being freed by Christ. We should remember who and what we were before Christ and we should relish in the fruit that is being produced and the freedom experienced in Christ Jesus. Apart from Christ, we work for our slave captors, which is the flesh. God calls his children to remember their slavery, and to enjoy their freedom.
As a believer, I am challenged to look back and see the slavery that I once was captive to, and to evaluate if I am surrendered to any of those old chains and to step forward and live in the freedom found only in Christ Jesus.