Does Liskov substitution principle apply to inheritance hierarchies where the parent is an abstract class the same way if the parent is a concrete class?

The Wikipedia page list several conditions that have to be met before a hierarchy is deemed to be correct. However, I have read in a blog post that one way to make things easier to conform to LSP is to use abstract parent instead of a concrete class.

How does the choice of the parent type (abstract vs concrete) impacts the LSP? Is it better to have an abstract base class whenever possible?