(Zumar) 39 : 14
قُلِ اللَّهَ أَعْبُدُ مُخْلِصًا لَهُ دِينِي
You say: I am serving Allah submitting my life exclusively to Him.
If it is told in verse 11 to say that indeed I am commanded to serve the Lord sincerely, submitting all life to Him, in this verse it is told to say that I am serving Allah, submitting my life exclusively to Him. And if I am not so, I will become aimless, entrapped by Satan. See explanation 7: 40; 36: 59-62; 38: 82-83.