Punishment of hell for the false witness

Hazrat Imam Muhammad al-Baqir (a.s.) says, 
"Whenever a person testifies falsely to usurp the property of a Muslim, Allah writes at that very moment a punishment of the blazing fire for this man." 
(Al Kafi)

Imam Ja'far as-Sadiq (a.s.) says, 
"The false witness may not even have moved from his place but that the punishment of fire will have already become incumbent for him." 
(Al Kafi)

The Holy Prophet (s.a.w.s.) says: 
"False testimony before an oppressive ruler is not yet complete when a place in the fire (Hell) is already decided (for the false witness)."
(Al Kafi)

The Messenger of Allah (s.a.w.s.) has also said, 
"One who testifies falsely against someone will be hung by his tongue with the hypocrites in the lowest portion of Hell.

And if one usurps the property of his believing brother, Allah does not give an increase in his sustenance till he repents for it." 
(Wasaelush Shia)

Hazrat Imam Muhammad al-Baqir (a.s.) narrates from the Holy Prophet (s.a.w.s.) that he said, 
"One who hides testimony before a just Islamic judge, or gives a false testimony to shed the blood of Muslims or intends to usurp a Muslim's property by it, he shall be raised on the Day of the Judgment in such a condition that there will be darkness before his eyes and his face will be scratched. The people shall recognise him by these signs (that he had testified falsely)." 
(Wasaelush Shia)

The Holy Prophet (s.a.w.s.) asked, 
"Shall I inform you about the Greater of the Great sins?"

The companions said, "Why not, O! Prophet of Allah (s.a.w.s.)." The Prophet (s.a.w.s.) said, 
"To make someone a partner of Allah, and disobedience to parents..." The Prophet (s.a.w.s.) was resting his back against the wall. Now he sat up straight and continued in a more serious tone, "And beware! (Every) Falsehood!"

The narrators say that the Holy Prophet (s.a.w.s.) has denounced falsehood so many times that we wished he had not done so. 
(Mustadrakul Wasael)

Since we have already explained that 'falsehood' includes every type of lying it also includes false testimony. The Holy Prophet (s.a.w.s.) has also described 'falsehood' to be a Greater sin. False testimony is a manifold sin. Firstly because it is a lie which is a greater sin, secondly because it amounts to falsely accusing a Muslim which is also a greater sin and thirdly because it is instrumental in oppressing an innocent person which is still another greater sin. Also, through false testimony a person tries to acquire something which does not rightfully belong to him, thus making unlawful thing lawful, which is prohibited by Allah. Lastly usurping somebody else's property is also a greater sin. Thus we can say that many great sins constitute a single sin called, 'false testimony'.

One should testify only after knowing the facts
It does not make any difference whether one knowingly gives a false testimony or one testifies without being certain of the facts. Both of these are 'Greater sins'. It is wajib upon the witness not to testify till he is confident of the facts.

Hazrat Imam Ja'far as-Sadiq (a.s.) says: 
"Do not testify till you are as certain as you are about the palm (of your hand)." 
(Wasaelush Shia)

Someone inquired from the Holy Prophet (s.a.w.s.) as to when it was allowed to testify as a witness. The Prophet (s.a.w.s.) told him:
"Can you see the sun?"

"Yes," he said. 
"Testify like it or do not." (Meaning you should testify only if you are absolutely certain, otherwise you must not do so). 
(Wasaelush Shia)

Hazrat Imam Muhammad al-Baqir (a.s.) says, 
"The witness should testify only for that about which he is certain. He must fear Allah. To testify without having certainty or to testify against something without being certain is also falsehood. Allah (a.j.) says, 
Refrain from falsehood! And remain upright for (the sake of) Allah and do not be among the polytheists.

So, Allah has equated false testimony to polytheism."
(Mustadrakul Wasael)

One who testifies falsely is soon exposed

If a person testifies in an Islamic court and later regrets for his testimony, then it is first determined whether he had knowingly and intentionally testified wrongly. If it was so, then that person is branded as a transgressor whose testimony is no more valid in the Shariat Court. But if he had been a victim of doubt and uncertainty he is not disqualified from testifying in the future. However, if due to the wrong testimony someone had to undergo undeserved punishment or suffer harm, it is wajib for this witness to make up the loss. The details of such laws could be obtained from the books of Jurisprudence.

One of the methods of disproving a testimony is that the witness himself confess it to be false. Another procedure for this is that two just witnesses may testify against him. This is known as 'Bayyana'. Finally, the judges may on the basis of some firm evidence falsify the testimony of a witness who had tried to mislead the court. Hence the judge is empowered to reject a witness if he is himself certain. If someone has suffered a loss the judge shall impose on the witness some exemplary punishment of a few lashes so that he may not repeat such a crime in future.

The judge should also announce in the city and the surrounding areas that such and such person is a false witness so that people may not be misled by him and may not rely upon his evidence. In this way, one who testifies falsely becomes notorious for his falsehood in the society, and the wellbeing of society is maintained. Both these actions i.e. exemplary punishments and warning the people against a false witness, are put into effect whether the judge has already passed his judgment (based upon that false testimony) or not.

They do not qualify as a witness

Imam Ja'far as-Sadiq (a.s.) is reported to have said, 
"The false witness must be lashed, and the number of lashes is determined by the Imam (or the Islamic judge) and he should be paraded (in the city) till people know him (and may not rely on him in the future)."

The Imam (a.s.) recited the following verse of the Quran: 
"...and do not admit any evidence from them ever; and these it is that are the transgressors, except those who repent after this and act aright, for surely Allah is Forgiving, Merciful."
(Surah Nur 24:4-5)

(It means that after he repents and reforms, his evidence again becomes valid)

The narrator says that he asked Imam (a.s.), "How do we know that he has repented?"

Imam (a.s.) replied, 
"At the site where he is lashed, he must confess in public that he had given a false testimony. And he must seek the forgiveness of Allah. In this way it could be known that he has repented." 
(Wasaelush Shia)

Compensation for the loss

If, due to a false testimony a Muslim has had to suffer some monetary loss or loss to one's life or property, the witness has to make good the loss. A narrator by the name of Jamil inquired from Imam Ja'far as-Sadiq (a.s.) regarding the one who has testified falsely. Imam (a.s.) told him: 
"If the disputed property is still intact it must be restored to the rightful owner. If it is not then the false witness is responsible to the extent of it's loss." (Masaalik)

This means that if it is not possible to return the property, the false witness will have to reimburse it by providing a thing similar to that property or pay a price for it. Detailed laws are discussed in the books of Islamic Jurisprudence.

Repentance for the sin

The method of repenting for the sin of giving false testimony has already been explained. The first important requirement is that the sinner must feel a deep remorse for the act committed by him. He must also seek the forgiveness of Allah for disobeying His command; and compensate the Musilm who suffered the loss. As Allah Himself says, 
"…except those who repent after this and act aright, for surely Allah is Forgiving, Merciful." 
(Surah Nur 24:4-5)