Sahih Bukhari

I heard Allah's Messenger (ﷺ) saying, 'Both legal and illegal things areevident but in between them there are doubtful (suspicious) things andmost of the people have no knowledge about them. So whoever saveshimself from these suspicious things saves his religion and his honor.And whoever indulges in these suspicious things is like a shepherd whograzes (his animals) near the Hima (private pasture) of someone elseand at any moment he is liable to get in it. (O people!) Beware! Everyking has a Hima and the Hima of Allah on the earth is His illegal(forbidden) things. Beware! There is a piece of flesh in the body ifit becomes good (reformed) the whole body becomes good but if it getsspoilt the whole body gets spoilt and that is the heart.