Firstly, as Imam an-Nawawee - rahimahullaah

Backbiting (Gheebah)

Firstly, as Imam an-Nawawee - rahimahullaah - said that one should remember the punishment of Allaah. And remember that Allaah is the Lord of the heavens and the earth. He is the One, aware of ever saying, at every time. Then if one remembers this, then it is only natural that one will be modest and shy in this aspect. We need to realize that when one of us is hurt, when something wrong is said about the creation, then what about the Creator, who is the All-Seeing and All-Hearing.

Secondly, we should reflect on the Qur'anic verse, “Do not backbite each other, would any of you wish to eat the flesh of your dead brother, no rather you hate it!!” [Surah Al-Hujarat 49:12]

And we surely hate even the thought of it.

Thirdly, fear that your own faults would be revealed, as the Messenger of Allaah - sallAllahu 'alaihi wa sallam - said,
“O you who believe with your tongues, yet Imaan has not entered your hearts. Do not backbite the Muslims, nor follow their faults. For he who follows others faults then Allaah will declare (disclose) his faults and he whom Allaah reveals his faults, then Allaah disgraces him in his own house.” - Sunan Abu Dawood (3/4862) and and authenticated by Sheikh al-Albani in Saheeh Jaami’ Sagheer

Fourthly, take the advice of the pious scholars of Islam, among them ….
Umar ibn Khattab - radiAllahu' anhu - who said, “Be careful from remembering people for it is an illness and be in the remembrance of Allaah for it is a medicine.”

A man came to al-Hasan al-Basri - rahimahullaah - and said that, he heard that al-Hassan al-Basri had backbitten him. Upon this he - rahimahullaah - said, “Who are you that I may give you my rewards?”

Fifth, and the most important thing to keep in mind is that there is a great reward to refrain from backbiting, as the Messenger of Allaah - sallAllahu 'alaihi wa sallam - said, “Whoever protects the honor of his brother in his absence, Allaah will protect his face from the Fire on the Day of Judgment.” - Sunan at-Tirmidhi and and authenticated by Sheikh al-Albani in Saheeh Sunan at-Tirmidhi (2/1575)