Allah Almighty says: {Do not follow that of which you have no knowledge} [Surat al-Isrā’: 36] And He says: {Not a single word he utters but there is with him a vigilant watcher, ready [to record it].} [Surat Qāf: 18]
1) One should not pursue what he does not know and must talk only about what he has knowledge about.
2) Awareness of the implications of mindfulness of Allah Almighty entails that one should only say beneficial words.
1547/1- Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah’s peace and blessings be upon him) said: “It is sufficient lying for a person to narrate everything he hears.” [Narrated by Muslim]
1) One must verify the authenticity of what he says or conveys of news.
2) Reporting everything that one hears is bound to make him fall into lying.
1548/2- Samurah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah’s peace and blessings be upon him) said: “Whoever reports a Hadīth on my authority that is thought to be false is one of the two liars (the one who fabricated it and the one who reported it).” [Narrated by Muslim]
1) One of the worst forms of lying is to lie about Allah Almighty and His Messenger (may Allah’s peace and blessings be upon him) because it involves promoting rulings that spoil people’s religiosity and beliefs and cause the destruction of lands and people.
2) It is prohibited to narrate fabricated Hadīths, and Muslims are warned against doing this.
Some orators and preachers take lightly the matter of narrating fabricated Hadīths, holding that doing this is permissible when it comes to speaking about virtuous deeds. To those people we say: Are not the authentic Hadīths of the Prophet (may Allah’s peace and blessings be upon him) sufficient in this respect? Why should we give up what is authentic and opt for the weak, when Allah Almighty says: {And do not follow that of which you have no knowledge}, And the Prophet (may Allah’s peace and blessings be upon him) said: “It is sufficient lying for a person to narrate everything he hears.” Al-Hāfizh Ad-Dāraqutni (may Allah have mercy upon him) (d. 385 H) said:
“Whoever narrates all the reports attributed to the Prophet (may Allah’s peace and blessings be upon him) without verifying the authentic and inauthentic thereof and the true and false thereof, has committed a sin and is feared to be counted among those who fabricate lies about Allah’s Messenger (may Allah’s peace and blessings be upon him).” [Introduction to Al-Du‘afā’ wal-Matrūkīn]
1549/3- Asmā’ (may Allah be pleased with her) reported that a woman asked Allah’s Messenger (may Allah’s peace and blessings be upon him): “I have a co-wife; is it sinful for me to boast (before her) of receiving from my husband what he has not given me?” He replied: “The one who boasts of receiving what he has not been given is like the one wearing two garments of falsehood.” [Narrated by Al-Bukhāri and Muslim]
-- The one wearing two garments of falsehood: one who deceives people by dressing like the people of asceticism or knowledge or wealth, so that people believe him to be so while he is not. There are other explanations for that, and Allah knows best.
1) The greater the evil caused by lying, the graver its sin.
2) A wive is warned of seeking to spoil the relationship between her husband and her co-wife.