marudzący po angielsku:

Stop grumbling.

My grandfather was always grumbling about something or other.

She would often hear him grumbling to himself.

I'm fed up with her grumbling.

... heard people mumbling and grumbling--" I have heard it...

Stop your grumbling and get the work out of the way.

Certainly she wouldn't have dreamt that I would get up promptly without grumbling.