When Muhammad bin Abi Sufyan was on his deathbed, he faced great hardship. (At that time) he said that my sister Umm Habibah bint Abi Sufyan narrated to me that the Messenger of Allah (peace be upon him) said: "Whoever performs four rak‘ahs with diligence and regularity..." Ibn Ma‘mar's wording is: "Whoever performs four rak‘ahs before Zuhr and four rak‘ahs after it, Allah will make the Hellfire forbidden for him."