Narrated Abu Hurairah: Allah's Messenger (peace be upon him) said,
"He who believes in Allah and the Last Day must not harm his neighbour, and he who believes in Allah and the Last Day must show hospitality to his guest, and he who believes in Allah and the Last Day should speak good or remain silent." (Bukhari and Muslim)
I wonder if the underlined part is also related to another hadith narrated by Ibn Umar,
"he who covers up (the faults and sins of a Muslim, Allah will cover up (his faults and sins) in this world and in the Hereafter." (Bukhari and Muslim)
Are you speaking good if you're speaking badly about others? Even if it's minor things? For example "She talks too much." Is there a such thing as a neutral category? It would be interesting to spend a whole day analyzing everything that comes out of my mouth and classifying it as good/neutral/bad and then eliminating all the bad stuff. I wonder how much silence would ensue thereafter.