The ministry of the Word, of course, refers most directly to biblical teaching. Right from the begining of the Church we see the importance of the teaching ministry of the apostles: the Christians 'continued steadfastly in the apostles' doctrine' (Acts 2:42). But the importance of the Word is also seen in other aspects of the apostles' ministry. Here are just a few examples.
One of the responsibilities of the apostles in Scripture is the appointment of elders. In Acts 14:23 we learn that it was the apostles Paul and Barnabas who 'appointed elders in every church'. The context of prayer and fasting suggest that this was not simply a human decision. Yet, whether called through the prophet (as Paul and Barnabas themselves had been - Acts 13:2), or by revelation to the apostles, the appointment of elders must still be subject to the authority of Scripture. Scripture lists qualifications for elders in 1 Tim 3:1-7 and Titus 1:5-9. Thus anyone appointed as an elder must meet these qualifications. The Bible is a higher authority than either prophetical ministry or revelation received by the apostleship: prophecy and revelation are subject to Scripture and evaluated by Scripture.The apostles also have a final responsibility for church discipline. Yet discipline is not to be exercised arbitrarily, but rather, in accordance with the Word.
Another responsibility of the apostleship is 'the care of all the churches' (2 Cor 11:28). An example is seen in Acts 15 with the Council of Jerusalem. When James concluded the council, he appealed to the Old Testament Scriptures for authority for the decision which had been reached. The apostles and elders listened to the experiences of Peter, Paul and Barnabas, but that was not sufficient. They needed the authority of Scripture. The apostles could not simply decide for themselves; their decisions were subject to the higher authority of the Bible.
So, in every aspect of their ministry, the authority of the apostleship is subject to the ultimate authority of Scripture. Not only can we believe both in present-day apostles and Sola Scriptura, but moreover we should believe in both. A belief in present-day apostles without Sola Scriptura is not a belief in the true biblical doctrine of apostleship. In the words of the Book of Common Prayer, that which 'God hath joined together let no man put asunder.'
Again, to borrow from liturgical language, 'Here endeth the lesson.'