2 John 1:12

Having many things to write— Perhaps this lady, or her children, might have several difficulties to propose to the apostle, which he could answer more directly and largely in conversation; or there might be several particulars with respect to the names, characters, behaviour, and doctrine of the false teachers, which St. John might not think proper to commit to writing. When he had said enough in this letter to guard against the present danger, he deferred saying more, till he had an opportunity to visit and converse with them.