Whoever believes in Allah and the Last Day should say what is good or keep silent

Authentic

عن أبي هريرة رضي الله عنه عن رسول الله صلى الله عليه وسلم قال: «مَنْ كَانَ يُؤْمِنُ بِاللهِ وَالْيَوْمِ الْآخِرِ فَلْيَقُلْ خَيْرًا أَوْ لِيَصْمُتْ، وَمَنْ كَانَ يُؤْمِنُ بِاللهِ وَالْيَوْمِ الْآخِرِ فَلْيُكْرِمْ جَارَهُ، وَمَنْ كَانَ يُؤْمِنُ بِاللهِ وَالْيَوْمِ الْآخِرِ فَلْيُكْرِمْ ضَيْفَهُ».

Abu Hurayrah (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) said: "Whoever believes in Allah and the Last Day should say what is good or keep silent. Whoever believes in Allah and the Last Day should honor his neighbor. Whoever believes in Allah and the Last Day should honor his guest."

Explanation

The Prophet (may Allah's peace and blessings be upon him) pointed out that a person who believes in Allah and the Last Day, that he will be resurrected and recompensed therein for his deeds, is driven by his belief to do these things: First: good words: Examples of good words include glorification of Allah and proclamation of His oneness, enjoining the right and forbidding the wrong, and reconciling between people. If a person does not say something good, he should then keep silent, restraining his tongue and sparing people from his harm. Second: honoring the neighbors: by being benevolent to them and not causing them any harm. Third: honoring the guests: by speaking to them in a nice manner, presenting food to them, and so on.

Benefits

Belief in Allah and the Last Day is the basis of all goodness, prompting people to do good.
The Hadīth warns against the bad use of the tongue.
Islam is a religion of cordiality and generosity.
These traits fall under the branches of faith and belong to sublime ethics.
Speaking a lot may lead one to what is disliked or prohibited. Safety lies in keeping silent unless one says something good.

Source · Agreed upon

From the Hadith Encyclopedia (hadeethenc.com).