An answer to a FAQ notes:
The effect size of a covariate may be high, even if it is not significant.
Does anyone know of papers I can reference to support that assertion?
FWIW, I do understand why it's true, i.e. I am not looking for an argument explaining why that fact is true. A citation to a published paper is useful to convince some non-mathematicians of it in a space-limited context.
The specific context is that I'm working with researchers in a field where it's normal to test a potential covariate for significance and then drop it if it's not significant. (Worse, the test is usually a univariable test.) The discussion in Harrell's RMS is excellent, but I'd prefer to cite short papers on the topic if they are out there.