In the year 1258 AD (675 A.H), there lived a tyrant Mongolian leader by the name of Hulagu Khan (Halaku), who invaded Baghdad and killed thousands of Muslims. This paved the way for Christian missionaries to preach Christianity and convert Muslims openly. Hulagu himself was married to a Christian woman.
One day, a delegation of the most notable Christians headed for Baghdad to attend a grand party to celebrate the conversion of a key Mongolian leader to Christianity. The Mongolian leader had his favourite hunting dog on a leash nearby.
One of the Christians then began congratulating the Mongolian leader on his wise decision and then proceeded to revile the blessed character of our Beloved Rasul (sallallahu alayhi wasallam [Supposedly in order to discourage them from accepting Islam].
The dog started acting violently and jumped on the Christian, scratching him badly. It took several men to make the dog let go of the Christian. One of the attendees turned to the Christian and said, “The dog did this because of what you said about Muhammad (Sallallahu alayhi wasallam).”
The Christian brushed aside the man’s comment and arrogantly said, “No, that was not the reason for the dog’s reaction. When I was speaking, I pointed with my hand and the dog thought that I was going to hit him.”
The Christian appeared unmoved by the incident and continued to insult the Holy Prophet (sallallahu alayhi wasallam). At that time the dog, in such a rage, cut itself loose, jumped on the Christian and sank its molars in the man’s neck. It snatched his throat out and the man died immediately.
This incident caused 40,000 Mongolians who were present there to embrace Islam.
[Ad-Durar Al-Kaaminah, Vol.2, p. 202]
[The commander here was Berke Khan Rahimahullah, who after accepting Islam, defeated many hordes of his Mongol cousins and freed many Muslim lands].
Imam Adh-Dhahabi said that this narration has an authentic (Sahih) chain in Mu’jam Ash-Shuyookh (387)