This quotation comes at the very end of Chapter 11 when Janie and Tea Cake agree to attend the Sunday School picnic together and, in effect, announce their relationship to the town of Eatonville. Tea Cake's words here are a biblical allusion and basically meant to inform Janie that she holds the keys to his heart and that he is completely head-over-heels in love with her.
This is an important statement for Tea Cake to make as we see the beginnings in this chapter of Janie's somewhat recurring doubts of Tea Cake's love and her apprehensions about engaging in a relationship with someone considerably younger. Janie's fears, of course, ultimately prove to be unfounded, but at this point in the novel Janie is unsure of the wisdom of this path. She ultimately acts based upon her heart and not on her mind.