Concept:This hadith teaches that true faith is shown through good speech and good conduct toward others.Explanation:In An-Nawawi's Hadith 15, the Prophet stressed practical signs of a believer. A person should say only what is good, or keep silent. The believer should also be kind to his neighbour and treat his guest well. This is the kind of conduct that proves one's faith in Allah and the Last Day. The hadith is not mainly about judgement, intention, or prayer. It teaches that we should treat other people the way we would like them to treat us.Answer:B. Should do unto other as we expect from them.