The String Quartet No. 19 in C Major, K. 465 by Mozart, nicknamed "Dissonance" on account of its unusual slow introduction, is perhaps the most famous of his quartets. It is the last in the set of six quartets composed between 1782 and 1785 that he dedicated to Joseph Haydn.
(you will have to listen on Spotify to hear the impressive slow introduction)
Playlist of all the music I have shared: https://goo.gl/i6DApN