Question 21: Is it permissible to kiss the hands of the clerics of religion?
Answer: It is not permissible to kiss the hands of the clerics of religion, because kissing the hand is not permissible unless it is the hand of a prophet or successor, as Imam Jafar Al-Sadiq pbuh said. The narration is in the book Usool Al-Kafi. 
Thus every single cleric of religion who presents his hand to be kissed, or is satisfied by this action and allows people to kiss his hand, is disobedient to the command of Allah, His Messenger, the Imams, and Imam Al-Mahdi pbuh. And the clerics must be humble, and submit to the command of Allah, His messenger, the Imams, and Imam Al-Mahdi pbuh, and they must obey what comes from him pbuh, and not become proud and raise themselves above the people, and present their hands to be kissed, imitating the emperors and tyrants. And I ask Allah to guide them except for whoever refuses and disbelieves.
The Allegories – volume 1
 The narration that Imam Ahmed Alhasan pbuh referred to is from Ali bin Mazeed, and he said that he met Imam Abu Abdullah pbuh, and he took his hand and kissed it, so he pbuh said, “It is only for a prophet or a prophet’s successor.” Al-Kafi Vol. 2 page 185.