I've been coming across the verb "diligence" more and more in internal documents (either as "to diligence" or "diligencing"). I was under the impression that this word could only be used as a noun. I found an interesting article about using diligence as a verb, but it's quite old (2009). I have not found any dictionary or style guides that support the use of the word "diligence" as a verb. Does anyone have any reliable sources to share that would support this use? Is it perhaps considered an acceptable expression in business jargon? The context is investment funds, if that helps.