Shaykh Saalih al-Fawzaan said:
The way of Ahl al-Sunnah wa’l-Jamaa’ah is to love the family (ahl al-bayt) of the Prophet (peace and blessings of Allaah be upon him).
The Naasibis love the Sahaabah but hate the family of the Prophet (peace and blessings of Allaah be upon him), hence they were called Naasibis because they set themselves up (nasb) as enemies of the family of the Prophet (peace and blessings of Allaah be upon him).
The Raafidis [the Shia] are the opposite: they love the Prophet’s family (ahl al-bayt) – or so they claim, but they hate the Sahaabah, whom they curse, denounce as kaafirs and criticize.
Shaykh al-Islam Ibn Taymiyah said, explaining the ‘aqeedah of Ahl al-Sunnah wa’l-Jamaa’ah: They (i.e., the Sunnis) love the people of the household of the Messenger of Allaah (peace and blessings of Allaah be upon him); they regard them with love and loyalty, and they heed the command of the Messenger of Allaah (peace and blessings of Allaah be upon him) concerning them… but they reject the way of the Raafidis [the Shia] who hate the Sahaabah and slander them, and they reject the way of the Naasibis who insult Ahl al-Bayt in words and deed…
Al-‘Aqeedah al-Waasitiyyah, Majmoo’ al-Fataawa, 3/154.
Undoubtedly rebelling and hating the Ahl al-Bayt and other Sahaabah is a serious kind of bid’ah (innovation) that implies slandering this religion which was transmitted to us via the Sahaabah, the Ahl al-Bayt and others.
Shaykh al-Islam Ibn Taymiyah said: “With regard to Ahl al-Sunnah, they regard as friends all the believers. When they speak it is on the basis of knowledge and fairness, unlike those who are ignorant or follow their whims and desires; they reject the way of both the Raafidis [the Shia] and the Naasibis and they hold all of the early generations in high esteem, and they recognize status and virtue of the Sahaabah and respect the rights of Ahl al-Bayt as prescribed by Allaah…”
Among the books which speak of the Naasibis and refute them and their ideas, and discussed those who went to the other extreme, namely the Raafidis [the Shia], is Manhaaj al-Sunnah by Shaykh al-Islam Ibn Taymiyah. You can refer to this book or some of its abridged editions.