Can Shia Brothers explain this term Nasibi?

Re: Can Shia Brothers explain this term Nasibi?

^Mohammad bin Abi Bakr, may Allah reward him, was a great lover of the AhlulBayt and a great companion of Imam Ali who treated him like his own son.

Mohammad bin Abi Bakr was an extremely intelligent, pious man who repeatedly told his sister Ayesha not to unplease the Allah and his Prophet by going out to fight against Imam Ali. Indeed Imam Jafar as Sadiq (AS) was very proud to have his mother related to a man such as Mohammad Bin Abi Bakr.

By the way, since you mentioned this great man, what are yours views regarding his Nasibi killers who killed him brutally?