Sunan an Nasai
4127
Sahih+2

It was narrated that 'Abdullah said:"The Messenger of Allah [SAW] said: 'Do not revert to disbelievers after I am gone, striking the necks of one another (killing one another). No man is to be punished for the sins of his father, or the sins of his brother

SahihAbu Ghuddah
SahihAl-Albani