Is it possible to not differentiate through an undefined variable?

Suppose I have some $ \lambda$ that is a function of $ x$ , and I don’t know exactly what it is yet.

Then, doing the following differentiation D[lamb, x] gives zero. But what I really want is to not have Mathematica evaluate the expression, i.e., just leave it as it is until I know $ \lambda$ later.

Is there a way to achieve this? Thanks!