عَنِ الْبَزَنْطِيِّ عَنِ الرِّضَا اَنَّهُؑ كَتَبَ اِلَيْهِ قَالَ اَبُو جَعْفَرٍؑ لَا يَسْتَكْمِلُ عَبْدٌ الْاِيمَانَ حَتَّى يَعْرِفَ اَنَّهُ يَجْرِي لِآخِرِهِمْ مَا يَجْرِي لِاَوَّلِهِمْ فِيْ الْحُجَّةِ وَ الطَّاعَةِ وَ الْحَلَالِ وَ الْحَرَامِ سَوَاءً وَ لِمُحَمَّدٍ ﷺ وَ اَمِيرِ الْمُؤْمِنِينَؑ فَضْلُهُمَا
Bazanti reports that Imam al-Reza (peace be upon him) wrote to him that Imam Muhammad al-Baqer (peace be upon him) said, “The faith of none will be complete till he recognizes that whatever is applicable for the first infallible (peace be upon him) is equally applicable to the last infallible (peace be upon him) vis-à-vis divine proof, obedience, permissible and prohibited things. Of course, Muhammad (peace be upon him and his holy progeny) and Ameerul Momineen (peace be upon him) are the most superior of all of them.”
Note:
All the fourteen infallible guides (peace be upon him) are equal in general excellences and merits like control of the universe, the power to legislate laws, the knowledge of the unseen, traversing the earth in a flash of a second, etc. But the Messenger of Allah (peace be upon him and his holy progeny) and Ameerul Momineen (peace be upon him) are the most superior of the fourteen infallible guides (peace be upon him).
References:
1. Behaar al-Anwaar, vol. 25, p. 353, H. 2
2. Qurb al-Asnaad, p. 152