Insaan (the human being) is distinguished from all the other creations of Allah Ta’ala by his tongue (the various forms of communication that lead to progress or retrogress). Hence, he should ensure that he utilizes this tongue in only good and righteousness. However, it sometimes happens that he utilizes his tongue in evil and wrong.
Thus, just as a person can utilize his tongue correctly, by using it for the sake of Allah and Deen, and excel even the angels in righteousness and virtue, he can similarly misuse and abuse his tongue due to which he stoops lower than even the swine, dog and other such filthy beasts.
The Hadith mentions:
وهل يكب الناس في النار على وجوههم أو على مناخرهم إلا حصائد ألسنتهم (جامع الترمذي رقم 2616)
Is there anything that causes people to enter Jahannum, where they will fall on their faces into the fire, more than the harvest of their tongues? (i.e. the evil deeds that they earn through their tongues e.g. lying, slandering, backbiting, carrying tales, etc.)
(Malfoozaat Hazrat Moulana Muhammad Ilyaas (rahmatullahi ‘alaih) pg. 54)