whoever believes that Awliya' can benefit or harm, seeks the protection from them, or makes Du`a' (supplication) to them instead of Allah is a Mushrik (one who associates others with Allah in His Divinity or worship) even if they bear witness that there is no god but Allah, observe Sawm, and perform Salah because such good deeds become vain due to the Shirk of the person who offers them. Allah (Exalted be He) says:
And indeed it has been revealed to you (O Muhammad صلى الله عليه وسلم), as it was to those (Allâh’s Messengers) before you: "If you join others in worship with Allâh, (then) surely (all) your deeds will be in vain, and you will certainly be among the losers."
(Part No. 16; Page No. 548) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.