Explanation:

The boy smiled in my face and spoke so innocently that I could not mistrust him; and swore to be faithful to me and go all over the world with me. 

Answer: These lines occur in Chapter 3 of Daniel Defoe’s Robinson Crusoe. The lines present a clear pen picture of the character of Xury. 

Robison Crusoe escaped from the Moorish Africans at Sallee with the help of Xury, In other words, Xury was Crusoe’s liberator. While Crusoe and Xury were in the boat on their way to escape from Sallee, at one ponttCursoe tells Xury that if he (X) remains faithful to him (C), he (C) will make him (X) a great man. In case of his (X) failure to be faithful to him (C), he tells (C) him (X) of dire consequences that he (X) will be thrown into the sea. At such utterances of Crusoe, the boy only innocently smiled on his (C) face and “swore to be faithful” to him (C) throughout his (X) life: And Crusoe could not but believe in the spontaneous innocence and sincerity of the boy. 

Through this expression of Crusoe, Defoe offers us a full sketch character of Xury.