Falsehood is one of the grave sins. Lying is the basis of all foulnesses. It will destroy the society, ruin it, and destroy the reputation of its owner. People will not believe what a liar says and will not entrust him with anything. Almighty Allah says:

'Is not to Allah that sincere faith is due? As for those who take guardians besides Him, “We only worship them that they may bring us nearer to Allah.” Allah will judge between them regarding their differences. Allah does not guide the lying blasphemer.' (Surah az-Zumar, 3)

Falsehood is the most difficult and damaging action a person can have from his tongue. Allah informs us about the fabricator of lies:

'It is those who do not believe in Allah’s revelations who fabricate falsehood. These are the liars.' (Surah an-Nahl, 105)

That is, he who does not believe Allah and His signs will invent a lie against Him. Because he is not afraid of suffering. He is a real liar. Since lying is a grave crime, a believer should not approach it.