The most important part of the body is the heart as has been mentioned by our noble Prophet Muhammed – SallAllahu ‘alaihi wa sallam – in his saying, “Indeed there is a piece of flesh in your body that, if it be sound, then the whole body will be sound and if it be corrupt then the whole body will be corrupt. Indeed it is the heart.” – [Sahih al-Bukhari [1/49] & Sahih al-Muslim 
The heart is thus the port where all actions stem, whether good or evil. If the heart is good then the actions will be good and if the heart is corrupt then the actions will be bad. The heart is the place where Allah scans, as the Messenger of Allah – SallAllahu ‘alaihi wa sallam – says, “Allah does not look at your bodies nor your faces but he scans your heart and actions.” – [Sahih al-Muslim (4/6221)]
As for the heart, Allah has commanded us to love Him and His Messenger, to love the righteous people, to love that which Allah loves and to hate all which Allah hates. The tongue acts accordingly, because…. the tongue expresses what is in the heart.
The Tongue Expresses what is in the Heart:
If a person is good, it reflects in their saying. Allah has made it very easy for the tongue to move, and it is not difficult to realize that a person’s tongue moves much more as if compared to the limbs. So if a person is not careful about what he says, even a single saying of his can invalidate his actions. It is for this reason that the whole body warns the tongue saying, “Fear Allah concerning us, for we are (dependant) upon you. If you are upright then we will be upright and if you are corrupt then we will be corrupt.” – [Sunan at-Tirmidhi (1912), Mishkaat (4838) and Riyaadh as-Saleheen (2/1521)]
And at the same time, the tongue is a great blessing from Allah. If we look at the animals, who are unable to speak, we realize the importance of this great tool of communication.
The gratitude that we should show for this great blessing should include, using it for the obedience to Allah, for reading the Qur’aan, for seeking Knowledge, to enjoin good and forbidding evil. The prohibitions of the tongue are that you do not lie, abuse, use foul language, backbite and slander.
Allah says in the begining of Soorah al-Mumineen, “Indeed successful are the Believers, those who in their prayer have Khushoo’ (fear of Allah) and those who refrain from vain talk.” [Soorah Mumineen : 1-3]
Here Allah mentions that refraining from vain talk is a sign of the successful believers. Allah also mentions refraining from vain talk after he mentions al-Khushoo’. This is because too much talk makes the heart hard. It is not possible to reach the level of Khushoo’ (fear of Allah) unless one refrains from vain talk.
Imaam an-Nawawee – rahimahullah – mentions “Know it is incumbent upon all to guard their tongues from most speech, except a word that has some benefit in it….” – Kitaabul-Adhkaar
“And for those who take heed there is a constant reminder in the verse, “Not a word is said except that there is a watcher by him ready to record it.” – [Soorah Qaf (50):18]
The Messenger of Allah, Muhammed – SallAllahu ‘alaihi wa sallam – said, “Whoever believes in Allah and the Last Day should speak good or keep silent.”
Imaam ash-Shafiee – rahimahullah – said. “If you wish to speak then it is upon you to think before you speak. If you think there is good in it then speak and if not then do not speak.”
The earlier mentioned Qur’aanic verses, Hadeeth (sayings) of our noble Prophet and advices by the scholars of Islaam are a guide for those searching for salvation against vain talk. So before we talk, should we not ask ourselves….
? Will this saying of mine please Allah?
? Will this saying of mine bring me closer to Allah?
? Does this saying earn with it obedience to Allah?
If yes, then speak, otherwise one should keep quiet.
GUARDING YOUR TONGUE FROM ALL HARAAM:
The Messenger of Allah – SallAllahu ‘alaihi wa sallam – said,
“Guard your tongue, stay in your homes and weep over your sins.” –
[Related by Ibn Mubarak in az-Zuhd (no.134), Musnad Ahmed bin Hambal (5/259), Sunan at-Tirmidhi (2531) and authenticated by al-Albaanee in as-Saheehah (no.890)]
Also the Messenger of Allah – SallAllahu ‘alaihi wa sallam – said, “Most of the sins of the children of Aadam are from the tongue.” – [At-Tabaraanee (3/87/1-2). Authenticated by al-Haafidh al-Mundhiri in al-Targheeb (4/8)]
Narrated by Mughira bin Shu’ba – radiAllahu’ anhu – : The Prophet – SallAllahu ‘alaihi wa sallam – said,
“Allah has forbidden for you:(1) to be undutiful to your mothers, (2) to bury your daughters alive, (3) not to pay the rights of the poor and others (i.e. charity) and (4) to beg of men. And Allah has hated for you: (1) Qil and Qal (sinful and useless talk, like backbiting or that one talks too much about others), (2) to ask too many questions (in disputed religious matters, etc.), (3) to waste your wealth (by extravagance with lack of wisdom and thinking).” – [Sahih al-Bukhari (3:591)]
Abu Moosa al-Asharee – radiAllahu’ anhu – said, “O Messenger of Allah, which of the Muslims are better?” The Messenger of Allah, SallAllahu Alaihi Wa Sallam, said, “Those who do not harm the Muslims with their tongues and hands.” – [Saheeh al-Bukhari (1/10) and Saheeh al-Muslim (1/64)]
Sahl ibn Sa’ad – radiAllahu’ anhu – reported that the Messenger of Allah, SallAllahu Alaihi Wa Sallam, said, “Whoever guards what is between his jaws and legs. I shall guarantee him paradise.” – [Saheeh al-Bukhari (8/481). A similar narration can be found in Muwatta of Imam Malik (56/11) and Sunan at-Tirmidhi.]
When the Companion of the Prophet, Mu’adh ibn Jabal – radiAllahu’ anhu – asked the Prophet – SallAllahu ‘alaihi wa sallam – about that which would entitle him to enter Paradise and save him from the hell-fire, he – SallAllahu ‘alaihi wa sallam – mentioned the pillars of Islam and informed Mu’adh of the importance of the night prayers and of Jihaad. He – SallAllahu ‘alaihi wa sallam – then said, “Should I not inform you of the sheet anchor of all this?”, and then took hold of his tongue and said, “Exercise restraint on it.”. Mu’adh – radiAllahu’ anhu – enquired, “O Messenger of Allah, will we be held responsible for what we say with it?” Thereupon, the Messenger of Allah said, “Mu’adh, will anything else besides (irresponsible) talk cause the people to be thrown in the Hell-Fire upon their faces?” – [Sunan at-Tirmidhi and Riyaadh as-Saaliheen (2/1522)]
Most of the people who will enter the fire, will do so due to their tongues
So a Muslim must beware and learn to imprison the tongue from vain talk, for the Messenger of Allah – SallAllahu ‘alaihi wa sallam – said, “Every saying of the children of Aadam is cursed, except for the enjoining good and forbidding the evil or for the remembrance of Allah.” – [Sunan at-Tirmidhi]
And “The world and all that it contains is cursed, except for the remembrance of Allah and what supports it, and a scholar and a student.” – [Sunan Ibn Majah (no.4112) and and authenticated by Sheikh al-Albani in Saheehul-Jaami’ (no.3414)]
Abu Hurairah – radiAllahu’ anhu – reports on the authority of the Prophet – SallAllahu ‘alaihi wa sallam – that, “From the good Islaam of a man, is that he leaves that which does not benefit him.” – [Musnad Ahmed bin Hambal (4/132), Sunan at-Tirmidhi, Sunan Ibn Majah, al-Baihaqi in Shu’ab al-Imaan]
Imaam Ahmad – rahimahullaah – mentioned in his Musnad on the authority of Anas radiAllahu ‘anhu who relates that the Prophet – SallAllahu ‘alaihi wa sallam – said’ The eemaan of Allah’s servant will not be upright until his heart is upright and his heart will not be upright until his tongue is upright.” – Also mentioned in al-Mundhiri (3/234) and al-Iraqee in al-Ihya (8/1539)
One saying ! ! Subhan Allah:
Abu Hurairah – radiAllahu’ anhu – said that he heard the Messenger say, “Indeed a servant (worshipper of Allah) may say a word which he doesn’t realize and it will make him fall into the fire further than the East and the West.”
Abu Hurairah – radiAllahu’ anhu – also reported that the Prophet SallAllahu alaihi wa sallam said, “Indeed a servant may say a word from which Allah’s pleasure is gained and the servant does not realize it, Allah will raise him up levels. Indeed a servant may say a word from which Allah’s displeasure is gained and he does not realize it, Allah will put him in Jahanam due to it.” – Saheeh al-Bukhari (8/485), Al-Muwatta (56/6) and in Saheehul-Jaami’ of al-Albaani
Imaam Ahmed – rahimahullaah – along with at-Tirmidhi, an-Nasaai and Ibn Majah record a Hadeeth on the authority of the Sahabee, Fujani – radiAllahu’ anhu – who said, “O Messenger of Allah tell me something that I may be firm upon?”. He – SallAllahu ‘alaihi wa sallam – answered, “Say, My Lord is Allah and then be upright concerning it.” He asked, “What is the thing that you fear for most.” The Messenger of Allah – SallAllahu ‘alaihi wa sallam – took hold of his tongue and said, “This!”. – Musnad Ahmed bin Hambal, Sunan an-Nasaai, Sunan Ibn Majah and Sunan at-Tirmidhi