The Prophet has called the Qur'an and his Descendants as "thaqalayn" (two
precious things) because "thaqal" means a pure, chaste and preserved thing,
and either of these two were really so, each of them is the treasure of Divine
knowledge and a source of scholarly secrets and religious commandments.
For that reason the Prophet desired the people to follow them and to stick to
them and to secure knowledge from them. Among them the most deserving of
attachment is the Imam and Scholar of the family of the Prophet namely `Ali ibn
Abi Talib (Allah may honour his face) because of his great insight and
copiousness of knowledge which we have already described. (as-Sawa`iq almuhriqah,
p. 90)
