“Imam Ibnul-Qayyim Jawzeeyah (rahimahullaah) said:

‘He who gets himself in the habit of doing actions just for the sake of Allaah, there is nothing harder upon him than to do an action for other than Allaah. And he who gets himself in the habit of doing actions based upon his desires, or [an ulterior motive, such as praise from the people, or status, or position, or wealth] then there is nothing harder upon him than to try to do an action sincerely to Allaah.’” http://salaf-us-saalih.com/2013/09/07/al-ikhlaas-is-the-foundation-for-the-success-of-our-actions-and-the-success-of-the-one-doing-the-actions/”