Of course the first problem is that it is necessary to use words, and if you don’t, well… its simply not the gospel.
But nor, it seems, is it something that St Francis actually said. Mark Galli, author of Francis of Assisi and his world writes for Christianity Today:
This saying is carted out whenever someone wants to suggest that Christians talk about the gospel too much, and live the gospel too little. Fair enough—that can be a problem. Much of the rhetorical power of the quotation comes from the assumption that Francis not only said it but lived it.
The problem is that he did not say it. Nor did he live it. And those two contra-facts tell us something about the spirit of our age.
His conclusion? Preach the gospel—use actions when necessary; use words always.