Reformed theologians have regularly underscored the relationship between Word and sacraments.
The sacraments are appended to the Word for the purpose of confirming or sealing it.
The sacraments do not exist independently of the Word. It’s the Word that throws life into the sacraments.
Moreover, there is no grace that is unique to the sacraments. The same grace that is received through the Word is also received through the sacraments.
So Word and sacraments belong together as “two sides of the same divinely instituted instrumentality,” as Geerhardus Vos put it.
Even though Vos did not produce a lengthy treatise on the sacraments, he occasionally addressed the subject in his writings.
In a sermon entitled “The Gracious Provision,” Vos has the following to say about the relationship between Word and sacrament.
The word and the sacrament as means of grace belong together: they are two sides of the same divinely instituted instrumentality. While addressing themselves to different organs of perception, they are intended to bear the identical message of the grace of God—to interpret and mutually enforce one another….
Let us therefore be careful to key our preaching to such a note that when we stand as ministrants behind the table of our Lord to distribute the bread of life, our congregation shall feel that what we are doing then is only the sum and culmination of what we have been doing every Sabbath from the pulpit.