But a point that many laypersons are not aware of is that not only were Umar and Ali thus related by marriage, but similarly were Abu Bakr and Ali related by marriage. Shaykh Ehsan Elahi Zaheer writes:
Asma bint Umais, as is already mentioned, was the wife of Ali’s real brother, Jafar ibn Abi Talib. When he died, she was married to Abu Bakr. She also gave birth to Abu Bakr’s son named Muhammad. Ali (may Allah be pleased with him) appointed him the governor of Egypt. After the death of Abu Bakr, Ali ibn Abi Talib married her. A son named Yahya was born out of the marriage.
Shia References:
(1) Haqq al-Yaqeen, by Majlisi
(2) Kitab al-Irshad, by Mufid
(3) Jila ul-Uyoon, by Majlisi
(4) Majalis-il-Mu’mineen, by Shoshtri(ash-Shia Wa Ahlul-Bayt, p. 121)