What is the Sharee'ah ruling on having a banquet that is prepared in the name of a certain righteous Wali (‘Ally’ of Allaah) where there is mixing between men and women and wastage?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Such banquets are considered to be an evil religious innovation that a Muslim is neither permitted to make, attend or participate in their preparation. Rather, he is required to boycott them and warn others against them because of the false beliefs that underlie them.  People who make such banquets are so attached to the dead that they believe in their ability to bring about benefit or inflict harm. This is definite Shirk. Allaah The Almighty Says (what means): {Say, "Surely I invoke only my Lord, and I do not associate with Him anyone." Say, "Indeed, I do not possess for you [the power of] harm or right direction." Say, "Indeed, there will never protect me from Allaah anyone [if I should disobey], nor will I find in other than Him a refuge.} [Quran 72: 20-22]

The Prophet, sallallaahu ‘alayhi wa sallam, warned against religious innovations. He said that whoever introduces an act in religion that is not in accordance with his guidance, it would be rejected. [Muslim]  He, sallallaahu ‘alayhi wa sallam, also warned against introducing new matters in religion and clarified that every new matter in religion is considered a religious innovation, and that religious innovations lead astray and consequently lead to Hell. [Muslim]

Such banquets are forbidden for the aforementioned reasons in addition to the mixing between the two sexes which is prohibited as well as the squandering of wealth. Allaah The Almighty Says (what means): {And do not spend wastefully. indeed, the wasteful are brothers of the devils, and ever has Satan been to his Lord ungrateful.} [Quran 17: 26-27]

Allaah Knows best.