However, "intercession is mentioned in the Qurʾān with respect to angels praying for the believers and the Prophet praying for erring but repentant Muslims." Furthermore, it became an orthodox Islamic doctrine or "cardinal belief" that "Muḥammad will intercede for all Muslims on the Day of Resurrection." While this particular tenet practically remained unchallenged throughout Islamic history, the widespread Sunni and Shia practice of asking deceased prophets and saints for intercession by praying at their tombs have become contentious issues in the modern Islamic world, with all these different types of intercession often being labelled by Salafi/Wahhabi Muslims as a type of polytheism, in a manner akin to the attitude of many Protestants towards the Catholic and Eastern Orthodox practice of saint-intercession.