Speak
Like "say," the word "speak" refers to thoughts and feelings moving from our more internal spiritual levels to our more external ones -- and ultimately from the Lord, who is in a sense the most internal spiritual level of all. This is generally called "influx" and "perception" in the Writings, meaning they are thoughts and feelings that flow in in a complete way from the Lord, rather than being things we have to think about and figure out. On a number of occasions "speak" and "say" are used together; in these cases "speak" refers more to intellectual instruction in matters of thought and "say" refers more to feelings and affections that flow in directly.
Jeremiah 30:10-12
10
Therefore don't you be afraid, O Jacob my servant, says Yahweh; neither be dismayed, Israel: for, behold, I will save you from afar, and your seed from the land of their captivity; and Jacob shall return, and shall be quiet and at ease, and none shall make him afraid.
11
For I am with you, says Yahweh, to save you: for I will make a full end of all the nations where I have scattered you, but I will not make a full end of you; but I will correct you in measure, and will in no way leave you unpunished.
12
For thus says Yahweh, Your hurt is incurable, and your wound grievous.
