Two reasons

In The Name of Allah, The Most Merciful, The Bestower of Mercy.

Allah said:

وَإِن تَلْوُا أَوْ تُعْرِضُوا فَإِنَّ اللَّهَ كَانَ بِمَا تَعْمَلُونَ خَبِيرًا

And if you distort your witness or refuse to give it, verily, Allah is Ever Well-Acquainted with what you do. [Al-Nisa 135]

Allah, Glorified be He and free is He from all imperfections, mentioned the two reasons that necessitate concealing the truth, warning against them and issuing a threat regarding them. The first one is distortion and the other is refusal. For indeed, when the truth is evident and there is one who cannot find a way of repelling it, he either disregards it and does not mention it, thus, he becomes a mute devil; at times, he distorts and misinterprets it. The example of distortion is the misinterpretation and it is two types: distortion of the wording and distortion of the meaning. The distortion in wording occurs when it is uttered in a manner that does not necessitate the truth, either by adding to the wording, omitting from it, or substituting it with another.

Distortion of its true usage and confusing the listener through words and other than its intended meaning, similar to how the Jews would twist their tongues in greeting the Prophet, [i.e. saying “As-Saam Alaykum” (death be upon you) instead of “Assalaamu Alaykum” (peace be upon you)]. This is one of the two types of ndistortions.

The second type is the distortion of meaning, explaining the wording in manner that is not intended by the speaker’s intent, either through ignorance of what was intended or by omitting certain aspects of the intended meaning. This is distorting meanings, thus Allah said:

وَإِن تَلْوُا أَوْ تُعْرِضُوا فَإِنَّ اللَّهَ كَانَ بِمَا تَعْمَلُونَ خَبِيرًا

And if you distort your witness or refuse to give it, verily, Allah is Ever Well-Acquainted with what you do. [Al-Nisa 135] [Bada’i at-Tafsir Al-Jami Limaa Fassarahu Al-Imam Ibn Al-Qayyim 1/302]