Allah’s Messenger did not hate anything as strongly as he hated falsehood.

Hazarat Ayesha (RA) narrates:

“Allah’s Messenger (SAWS) did not hate anything as strongly
as he hated falsehood. If he received information that a particular
man has told a lie, he used to throw away that man’s respect
and honor from his heart till the time he was not informed that he
has repented for it.”

Another hadith states:

“When a person tells a lie, the bad odor that emanates from
it keeps the angels one mile away.”

Following things should be borne in mind to avoid falsehood.

We should not tell a lie even in a joke. The Prophet (SAWS) has said:

“Death for the man who indulges in story-telling in order to
make some people laugh and for that he relies on falsehood. There
is death for him, there is destruction for him.” (Tirmidi)

This is our daily observation that people give full rein to their tongues
in the matter of humorous talks to make others laugh, and do not hesitate
to spread the tales and stories invented by friends or foes only for
the purpose of getting some pleasure or for pulling someone’s leg.
In fact it is due to this kind of entertainment and amusements and false
acts that has created enmities and rivalries among us.

We should avoid exaggeration in praise. Some people when they praise
somebody go to the extent of exaggerating and making false statements.
For a Muslim it is necessary that when he praises somebody he should
do it to the extent to which he knows about that man. He should avoid
exaggeration and falsehood in showering the praises of the praised one,
although he may be deserving of praises, for exaggeration is a kind
of falsehood, which has been forbidden. To a person who was praising
the Prophet, he said:

“Do not indulge in exaggeration while praising me, as the Christians
did in the case of Jesus. I am only a slave, so only say that he is
a slave of Allah and His Messenger.”

We should keep away from falsehood and deception in trade and financial
dealings with others. Prophet (SAWS) said:

“It is not lawful for a Muslim to sell such a commodity that
has a defect, except that the defect is shown to the buyer.”
(Bukhari)

Never give false evidence while on oath, as it is perjury and a major
sin. When a Muslim should stand up for giving evidence, he should state
the truth unhesitatingly; regardless of the fact whether it is against
his close friend or relative. No relationship or prejudice should deviate
him from the right path, nor any greed or bribe should be able to make
him waver in his stand.

Never break a promise given to someone. We should take special care
to see that we keep our promises, be true to our words and not change
our stand. It is a very sad state of affairs that among the Muslims
the tendency of breaking promises and crossing limits has become very
common, when our religion has termed the false promises as symbols of
trouble.