Nothing was Rejected as Much as Imamah

5 - Qurb al-Isnad: Ali, from his brother, Musa (a.s.) who said, ‘He (a.s.) used to say before he passed away by a year, when his family members had gathered to him : God has not emphasized more upon the servants regarding anything what He has emphasized with the acknowledgment of the Imamate [al-Imamah], and the servants did not reject anything more than what they rejected it. [Bihar al-Anwar,Volume 23, Page 69]

5 - قرب الإسناد: علي، عن أخيه موسى عليه السلام قال: كان يقول قبل أن يؤخذ بسنة إذا اجتمع عنده أهل بيته: ما وكد الله (6) على العباد في شئ ما وكد عليهم بالاقرار بالإمامة، وما جحد العباد شيئا ما جحدوها