They have a history that goes back to the late 1980's. Nadler was in the New York Assembly and

Trump at the time was developing a massive project in Nadler's district, Manhattan's Upper West Side.

Nadler tried to stop the project but in the end Trump won and built his project.

https://www.realclearpolitics.com/articles/2019/01/03/nadler-trump_feud_to_resume_–_with_higher_stakes_139078.html