Victims of Backbiting – Take Comfort in the Wisdom of the Salaf

In the Name of Allaah, the Most Merciful, may His Salaah and Salaam be upon His last Messenger to all of mankind, to proceed…
It has been narrated that one of the great imaams of the early Salaf, ‘Abdur-Rahmaan ibn Mahdee [d.198] (may Allaah have Mercy on him), said:

لولا أني أكره أن يعصى الله لتمنيت أن لا يبقى أحد في المصر إلا اغتابني!  أي شيء أهنأ من حسنة يجدها الرجل في صحيفته لم يعمل بها؟

“If I did not hate that Allaah be disobeyed, I would have wished that there was no one left in the whole city except that he has backbitten me!  What is more rewarding than a man finding a good deed (written) in his book for something he did not even do?!”

Source: Siyar A’laam An-Nubalaa’ (9/195-196), Risaalah printing
ELABORATION
“If I did not hate that Allaah be disobeyed…”
Meaning that backbiting is haraam, and to wish that the Muslims would backbite would be wishing that Allaah be disobeyed.  However, to stress the benefit of being backbitten, he goes on to say:
“…I would have wished that there was no one left in the whole city except that he has backbitten me!”
When someone is backbitten or slandered, naturally he feels disturbed and upset, and even a sense of loss.  So people need someone to point out that there is a great amount of good in being the focus of people’s backbiting.  This advice of Abdur-Rahmaan ibn Mahdee seems to be from the idea of mutually advising each other to have patience, as mentioned in Soorah Al-’Asr.
Apparently, this was in response to him hearing that some people were talking about him, or possibly someone was complaining to him about having been backbitten, and Allaah knows best.  He says that if it was permissible to wish for others to fall into disobedience, he would have wished that they all would backbite him, and then he clarifies the reason for saying this:
“…What is more rewarding than a man finding a good deed (written) in his book for something he did not even do?!”
Since the one who backbites someone (in other than the permissible, sometimes obligatory, forms of backbiting) forwards to that person his good deeds or will be made to be accountable for bad deeds of his victim, as mentioned in the hadeeth of Al-Bukhaaree:

“The bankrupt one from my nation will come on the Day of Judgement with deeds of prayer, fasting, zakaah, but he has insulted this one, maligned that one, taken the money of this one, spilled the blood of that one, or hit another one.  So some of his good deeds will be given to this one and that one.  If no good deeds remain, then it will be judged that their bad deeds be taken and cast upon him, then he will be cast into the Fire.”

And we ask Allaah for protection.
So then his statement, “…a good deed (written) in his book for something he did not even do,” seems to be referring to what is mentioned in the hadeeth that the one who is maligned will be given some of the good deeds of the one who maligned him.
And Allaah knows best.