Issues in Ijtihād and Taqlīd3]

Answer: The scholars differ. Some say the truth in ijtihādī matters is
one; others say it is multiple. They are all agreed, however, that sin and
blame are lifted from the mistaken mujtahid, that he must act upon his
ijtihād, and that his followers are excused.
Accordingly, we may say: What the mujtahid’s reasoning leads him to
is correct, and his followers are correct in following him—whether or
not that ijtihād accords with truth in reality, and whether or not we say
that every mujtahid is correct.
Thus Imām Zayd b. ʿAlī (ʿa) said, as in his collected letters: “Our
differences are a mercy for you. But if we agree upon a matter, it is not
permissible for you to oppose us.” Or words to that effect.
The meaning of his statement (ʿa) is that the differences among the
scholars of the Ahl al-Bayt are a mercy and an opening for the people,
since it contains facilitation for them and choice in following one or
another opinion.