And the example of a bad word is like a bad tree, (14:26)

Almuntakhab Fi Tafsir Alquran Alkarim

Whereas an evil word stands similitude exact of an evil tree; it may flourish to begin with but soon enough it is uprooted from the soil and the surface of the earth. Its roots being loosely implanted, it does not have the strength to grow erect nor does it eventually grow at all

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(14:26) And an `evil word' *37 may be likened to an evil tree; which is torn out from the earth and has no stability. *38

And the example of a bad word is like a bad tree, meaning

*37) "Evil word" is the opposite of "Pure Word" It may be applied to everything that is unreal and wrong but here it stands for any false creed that one might adopt as a basis of one's system of life, irrespective of whether it be atheism or heresy or disbelief or shirk or idol-worship or any other "ism" that has not been brought by a Messenger.
*38) And "evil word" (false creed) has no stability because it is against the Law of nature. Therefore, everything in the universe opposes it and refutes it, as if the earth hates it and is ready to spit out its seeds every time they are sown in it, and if some need succeeds in growing an evil tree, heaven suppresses down its branches. In fact, false creed could never have been allowed to develop, if man had not been given the freedom of choice and respite for work for the sake of his trial. That is why when same foolish people exert to establish a system of life on it, it is allowed to grow to a certain extent, but it produces nothing but harmful results as long as it lasts. And no sooner dces it encounter with adverse circumstances than it is thoroughly uprooted from the earth.
The distinction between the "Pure Word" and the "evil word" is so apparent that anyone who makes a critical study of the religious, moral, intellectual and cultural history of the world can perceive it easily. For the "Pure Word" has always been the one and same during the whole history of mankind and has never been uprooted. On the contrary, there have been innumerable "evil words" but each and every one has been so uprooted that there has remained hardly anything of it except its name in the pages of history. Nay, some of these had proved to be so absurd that if these are mentioned today one wonders how one could have followed such nonsensical things.
There has been another noteworthy difference between the two "words". Whenever and wherever the "Pure Word" has been adopted by an individual or a community, its blessings had not been confined to that individual and community but had benefited all around them. On the contrary, whenever and wherever an evil word has been adopted by an individual or a community, its evils had spread chaos and disorder all around them.
In this connection, it should also be noted that the parable of the "Pure Word" and the "evil word" explains the same theme that had been explained by the similitudes of the mound of ashes that is blown away by the "wind" of the stormy day (v. f8) and of the "foam cf flood", and the "scum of the melted metals." (XIII: 17) C v a N
 

And the example of a bad word is like a bad tree, meaning in Urdu

اور کلمہ خبیثہ کی مثال ایک بد ذات درخت کی سی ہے جو زمین کی سطح سے اکھاڑ پھینکا جاتا ہے، اُس کے لیے کوئی استحکام نہیں ہے