O YOU who have attained to faith! No men shall deride [other] men: it may well be that those [whom they deride] are better than themselves; and no women [shall deride other] women: it may well be that those [whom they deride] are better than them­selves. And neither shall you defame one another, nor insult one another by [opprobrious] epithets: evil is all imputation of iniquity after [one has attained to] faith;  and they who [become guilty thereof and] do not repent - it is they, they who are evildoers!

A man asked the Prophet , "What sort of deeds or (what qualities of) Islam are good?" The Prophet replied, 'To feed (the poor) and greet those whom you know and those whom you do not Know