Does anybody recognize this from Douglas Adams' writings?

I very distinctly a passage where someone is given sodium pentothal and starts uttering great truths, culminating in the distillation of all the world’s religions into the two word phrase, “Be nice”.

I don’t have a copy of the Hitch Hiker’s Guide books, having borrowed them from the library. I did book searches on Amazon and could not find what I was looking for. Am I perhaps mixing up the works of Adams with someone else? I know I did not make this up on my own.