Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Umar''s marriage to Umm Kulthum bint Ali occurred in 17 AH (637 638), when Umar was 55 years old. The event is notable in that Shi''a and Sunni differ as to the identity of the person named Umm Kulthum. The Shias have argued against this Hadith by saying that the real Arabic text of this narration does not mention "the daughter of Ali" and that is in reality an addition by the translator, Dr. Muhsin Khan. The Sunnis, however, argued that this is a blatant lie and the actual narration does mention her to be "the daughter of Ali." The Shias also argued that this narration is unauthentic because one of its narrators is Thalabah ibn Abi Malik and he is a completely unknown personality. But the Sunnis showed that this is a lie as well.