In Acts 14:23 (narrative, descriptive) we read that it was the Apostle Paul's pattern to appoint Christian elders within churches early on in the lifecycle of a church (1):

Paul and Barnabas appointed elders for them in each church and, with prayer and fasting, committed them to the Lord, in whom they had put their trust.

Acts 6:1-7 provides the prototype for the ministry of deacons in the church. Without spirit-filled wise deacons, a church will undergo great distresses which presents the potential to fracture the church. If those who are dedicated to prayer and ministry of the word are tasked with the work of deacons, the church also suffers greatly. We can observe that these two roles in the church (ministry of prayer & word, and ministry of mercy) are both necessary.