A:
Salah which is performed behind an Imam who makes Du`a' to other than Allah or seeks their help, or offers sacrifices to other than Allah is invalid. This is because such an Imam is considered a Mushrik (one who associates others with Allah in His Divinity or worship) whose Salah is invalid, and so is the Salah of his Ma'mums (persons being led by an Imam in Prayer).May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.