(a) It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "When one of you forgets to pray a prayer and then remembers it while he is offering an obligatory prayer, let him continue the one he is praying. When he has finished it, then let him make up the one he had forgotten."
Abu Ahmad (Ibn Adi) said: Umar bin Abi Umar is majhul (unknown); I do not know anyone other than Baqiyyah who narrates from him.
(b) Shaykh al-Bayhaqi (may Allah have mercy on him) says: All the rulings of the prayer in which man and woman differ go back to covering, because the woman is commanded to do everything that gives her greater covering.
The coming chapters contain their details and the explanation of this meaning. And success is from Allah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3196