[The Zaydīs Are the Group of Truth, Even If Their Number Is Small]

It may be said in response: The Zaydīs, even if they are a small minority confined to one corner of Yemen, are nevertheless known throughout history by their Imam, Zayd ibn ʿAlī, and by their doctrines and schools among all Muslim scholars.
If the scholars of the various sects know the Zaydīs, their doctrines, and their schools, then the proof has been established against them.
It is not required of the rightful group to convey the truth and its proofs to every individual Muslim. Rather, it is sufficient that the scholars know it. The Messenger (May Allah bless him and his family and grant them peace) used to teach people the foundations of their religion, then he would say: “Let the one who is present convey to the one who is absent”. And Allah the Exalted said: "So why did not a group from every faction among them go forth to gain understanding in the religion and warn their people when they return to them, that they might beware?" [At-Tawbah:122]
- Allah the Exalted has also condemned the scholars of the Children of Israel for concealing the truth and remaining silent about conveying it to the people, in many verses of the Qur’an. This indicates that the scholars of the Ummah of Muhammad (May Allah bless him and his family and grant them peace) are obligated to convey to the people the truth they know, and that Allah’s proof against the people does not fall away due to the silence of scholars about disseminating and spreading it.
- It is astonishing that the Ummah of Muhammad (May Allah bless him and his family and grant them peace) turns away from the Ahl al-Bayt (Peace be Upon Them) and their schools, practicing religiosity through hatred of them, aversion toward them, and intense hostility against them—and so on. This phenomenon has appeared in the Ummah of Muhammad (May Allah bless him and his family and grant them peace) from the moment our chosen Prophet (May Allah bless him and his family and grant them peace) passed away, until today.
- What is well known is that the Ummah acknowledges the authentic hadiths concerning the Ahl al-Bayt (Peace be Upon Them), knows that they are authentically reported from their Prophet (May Allah bless him and his family and grant them peace), admits their authenticity from the Prophet (May Allah bless him and his family and grant them peace), and that scholars and students study them. Yet this knowledge does not deter them from the hatred and hostility they harbor toward the family of Muhammad (May Allah bless him and his family and grant them peace). Rather, despite all this, they profess religiously that loving the family of Muhammad is a grave sin that is not forgiven, and they hold that hostility and hatred toward them is part of faith and one of its pillars.
- You see them maintaining the prayers, paying zakāh, fasting, performing pilgrimage, and so on. In their outward religiosity, they appear to hope for Allah’s mercy, the intercession of the Prophet (May Allah bless him and his family and grant them peace), entry into Paradise, and attainment of Allah’s pleasure—and they believe themselves to be the people of truth.
- And I do not know how this notion became acceptable to them, despite their firmly established knowledge of what their Prophet—the Prophet of Islam (May Allah bless him and his family and grant them peace)—brought regarding the precedence of the Ahl al-Bayt (May Allah bless him and his family and grant them peace) in virtue, the obligation of loyalty to them and love for them, and that they are the people of truth who neither depart from it nor does it depart from them until the Day of Resurrection, and that they… and that they… and so on.

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.3