The text of today is from the latter part of the Sermon on the Mount. In it Jesus asks his listeners to focus on the internal i.e. the heart from which everything else flows. If the heart is pure than everything that a person does or says will also be pure. The external is only an expression of the internal. A person's actions or words flow from what is in his/her heart.
Our actions do not often coincide with our words, because we do not always mean what we say. Sometimes we say one thing and do another. There is a dichotomy between our words and actions. We are called to synchronise the two.