It is narrated from Hazrat Umm Atiyyah (may Allah be pleased with her) that when this verse was revealed, "They will pledge allegiance to you that they will not associate..." etc., wailing was also included in it. I said, "O Messenger of Allah, exempt the people of such-and-such family, because they helped me in wailing during the time of ignorance, so it is necessary for me to help them as well." So the Prophet (peace and blessings be upon him) exempted them.