Someone pointed out that Rabbi Dr. Twersky's article about Ibn Caspi didn't actually include citations on the topic of Dibra Torah. You can download Ibn Caspi's works at Hebrewbooks.org; his Mishna Kesef is here. Twersky has many references in the endnotes of his article, but here is one of the most important quotes, from page 49:

It's tricky to translate this into readable English. If someone has the time to do so, please post it in the comments.