The sin of finding faults in others!!
Many times we focus our efforts in directing faults of others, but we forget our ownself,
here are some advices/warnings for us to take lessons from, inshAllah
Hadith - Bukhari's Book of Manners #313, Ahmad, Ibn Hibban, and Hakim
... 'Abd Allah reported that the Prophet of Allah, upon him be peace, said, "A believer is not a fault-finder and is not abusive, obscene, or course."
Hadith - Bukhari's Book of Manners #329
... Ibn 'Abbas said, "If you wish to mention the faults of your friend, mention your own faults first."
Hadith - Bukhari's Book of Manners #330
... Ibn 'Abbas said on the following verse of the Qur'an, "Nor defame one another" (49:11), "Do not spend your time finding fault with one another."
Hadith - Bukhari's Book of Manners #545
Jubayr ibn Nufayr reported that Mu'adh ibn Jabal said, "If you love someone, do not quarrel with him and do not annoy him. Do not ask others about him, for the one you ask might be his enemy and thus tell you things about him that are not true and thus break you apart."
Hadith - Bukhari's Book of Manners #889 and Ibn Hibban
'Amr ibn al 'As said, "...I am amazed at one who spots an impurity in the eye of another but is unable to detect it in his/her own eye, or who attempts to remove a grudge from anothers heart while making no attempt to remove grudges from his/her own heart. I have never blamed anyone for the confidences of mine that they have betrayed. How could I, when already they have given me reason for pause?"
Hadith - Bukhari's Book of Manners #1295
Bilal ibn Sa'd al Ash'ari reported that Mu'awiyah wrote to Abu Darda' "Write to the wrongdoers of Damascus." So he asked, "What do I have to do with the wrongdoers of Damascus? How will I know them?" Abu Darda's son, Bilal said, "I will write to them," which he did. Then Abu Darda' said [to Bilal], "How did you know to whom to write? You could not have known they were wrongdoers unless you were one of them. Begin with yourself!" So he did not address the letter in anyone's name.*
*i.e. he didn't single out a specific person as a wrongdoer, but spoke about wrongdoings in general, to come as a reminder (of Quran and Sunnah) to the people.
Muslim :: Book 32 : Hadith 6267
Abu Huraira reported Allah's Apostle (may peace be upon him) as saying: The servant (who conceals) the faults of others in this world, Allah would conceal his faults on the Day of Resurrection.
Bukhari :: Book 8 :: Volume 73 :: Hadith 90 Narrated Abu Huraira:
The Prophet said, "Beware of suspicion, for suspicion is the worst of false tales; and do not look for the others' faults and do not spy, and do not be jealous of one another, and do not desert (cut your relation with) one another, and do not hate one another; and O Allah's worshipers! Be brothers (as Allah has ordered you!")
Muslim :: Book 30 : Hadith 5723
Anas reported Allah's Messenger (may peace be upon him) as saying: I served the Messenger of Allah (may peace be upon him) for nine years, and I do not know (of any instance) when he said to me: Why you have done this and that, and he never found fault with me in anything.
Dawud :: Book 41 : Hadith 4870
Narrated Mu'awiyah:
I heard the Apostle of Allah (peace_be_upon_him) say: If you search for the faults of the people, you will corrupt them, or will nearly corrupt them. AbudDarda' said: These are the words which Mu'awiyah himself from the Apostle of Allah (peace_be_upon_him), and Allah benefited him by them.
Bukhari :: Book 8 :: Volume 73 :: Hadith 90 Narrated Abu Huraira:
The Prophet said, "Beware of suspicion, for suspicion is the worst of false tales; and do not look for the others' faults and do not spy, and do not be jealous of one another, and do not desert (cut your relation with) one another, and do not hate one another; and O Allah's worshipers! Be brothers (as Allah has ordered you!")
To save ourselves from this sin and many others, one should act upon this Hadith which deserves to be written in gold. The Hadith states, “Whoever stayed quiet saved himself.”
This very sin which Muslims consider right is the sin which could send many to hell. The Prophet said, “The tongue is what will cause people to be flung face down into hell.”
May Allah Taa'la save us from the hell fire and all sins that we have committed.
إملاء الخير خير من السكوت والسكوت خير من إملاء الشر
"Speaking what is good is better than silence, and silence is better than speaking evil."