Hakim al Umma Mawlana Ashraf Ali Thanawi (Allah have mercy on him) said,
‘Negligence in maintaining etiquette (adab) of friends of Allah (awliya) is forbidden.
Similar, and more worse, is the case of excessive and overenthusiastic attitude in this regards.
This is because, it diminishes the status of Allah and the Prophet.
For example, considering awliya to be ‘Alim ul ghayib‘ (having knowledge of ‘unseen’*). This (assumption) necessitates unbelief (kufr).
Allah says,
Say, “No one in the heavens and the earth has the knowledge of the Unseen except Allah.” [27:65]
Say, “I do not say to you that I have the treasures of Allah, nor do I have the knowledge of the Unseen, nor do I say to you that I am an angel. I only follow what is revealed to me.” ” [6:50]
“………….they encompass nothing of His knowledge, except what He wills.” [2:255]
Or considering them (awliya) to have powers to create or destroy something or give children or provision, etc. or coerce Allah to do so is also unbelief (kufr).
Say, “I have no power to bring a benefit or a harm to myself, except that which Allah wills.” [7:188]
Or to perform an act for them (awliya) from the (established) actions of worship (ibadaat). Like, intending a vow (nazar) in their name, or performing tawaf of their grave, or supplicating to them, or recitation of their name as form of worship. Some of these acts are sinful and innovation, and others are unbelief (kufr) and associating partners with Allah (shirk).
Allah says,
“You alone do we worship, and from You alone do we seek help.” [1:5]
The Prophet (Allah bless him and grant him peace) said,
“Tawaf (circumbulation) of the House (of Allah: ka’ba) is (like) salah.”
«الدعاء هو العبادة»
“Supplications (dua) is (form of) worship”.
Allah says,
“Your Lord has said, “Call Me, I will respond to you. Definitely those who show arrogance against worshiping Me shall enter Jahannam (Hell) with disgrace.” [40:60]
“Surely, those whom you invoke beside Allah are slaves (of Allah) like you.” [7:194]
Taleemud Deen, page 127-9