Implication: if you serve God for reward—that is bad.
Notice it is Satan that asked this question. God is all about reward. The original covenant with Abraham emphasizes that God will bless Abraham. In
Genesis 15.1 we read that God is Abraham’s great reward. The promise of reward and blessing is repeated in Genesis 18.18 and 22.17. It is repeated again to Abraham’s kids and grandkids.
My favorite verse teaches that you cannot come to God unless you believe that He exists (most people do) and that God is a rewarder (most people don’t). (Hebrews 11.6)
God is a rewarder. God is good. It is good to follow God. It is always in our best interest to live the Christian life. It is always good for us to follow God.
There is no conflict between what is good for me and what is good for God. You must believe that God is a rewarder or, according to Hebrews 11.6, you can’t come to God.
I don’t think this is saying God will reject you if you try to come to Him. It is just stating the nature of things—you won’t try to come to God unless you believe it is good for you to do so.