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!