Lexicon. No real context, just oft cited. It’s from Trout Fishing in the Reflecting Pool, or The Fireside Watergate. A mass market paperback, Nicholas von Hoffman wrote the text, and Garry Trudeau did single-panel, editorial page style cartoons. One shows senator Sam Ervin saying,

Ah am not bein’ harassin’ towards the witness. Ahm bein’ gruff, and lovable, and yew know it.

The book also has the only drawings I know of Nixon by Trudeau. (Nixon was always shown speaking without being seen, in Doonesbury.)