Sincere intention and devotion (ikhlas)

وَمِنَ ٱلنَّاسِ مَن يَشْرِى نَفْسَهُ ٱبْتِغَآءَ مَرْضَاتِ ٱللَّهِ ۗ وَٱللَّهُ رَءُوفٌۢ بِٱلْعِبَادِ

And of the people is he who sells himself, seeking means to the approval of Allāh. And Allāh is Kind to [His] servants.