Abdullaah Bin Muhammad [rahimahullaah] said:

Saeed Ibnul Musayyib [rahimahullaah] said to us: The servants have not been more honoured with [something] for their souls similar to obedience to Allaah [The Mighty and Majestic]; and they are not more degraded by [anything else] similar to disobedience to Allaah. [Hilyatul Awliyaa: 2/164]