Imam al-Shafi'i (may Allah have mercy on him) said: "So whoever establishes proof (testimony) for any of it (the goods), it is his; and whoever does not establish proof, then the analogy, which in my view no one is excused for overlooking, based on consensus, is that these goods are in the joint possession of both of them. So each of them will swear an oath against his companion's claim, and if both swear, it (the goods) will be divided between them half and half."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الدعوى والبينات / Q21295
Ibn Abi Mulaykah said that Ibn Abbas (may Allah be pleased with them both) wrote to me that the Messenger of Allah (peace and blessings be upon him) said: "The oath is upon the defendant."
Imam al-Shafi'i (may Allah have mercy on him) said: (This is also) because a man may own women's goods, and a woman may come to own a man's goods by purchase, inheritance and the like. Ali bin Abi Talib (may Allah be pleased with him) made Fatimah (may Allah be pleased with her) lawful for himself with a coat of iron armour (as dowry), and that is a man's item, yet at that time Fatimah (may Allah be pleased with her) was the owner of the armour, not Ali (may Allah be pleased with him).
The Shaykh said: Ikrimah narrates from Ibn Abbas (may Allah be pleased with them both): When Ali (may Allah be pleased with him) married Fatimah (may Allah be pleased with her), he (peace and blessings be upon him) said: "Give Fatimah something." He said: I have nothing. He said: "Where is your Hutami coat of mail?"
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الدعوى والبينات / 21295
Raqabah (may Allah have mercy on him) said: Yazid bin Abi Muslim came out from al-Hajjaj and said: The governor has given a judgement. Imam al-Sha'bi (may Allah have mercy on him) asked: What is it? He said: He said: Whatever is the man's belongs to the man, and whatever is women's belongs to the woman. Al-Sha'bi said: That is the judgement of a man from the people of Badr. He asked: Who is he? He said: I will not tell you.
He said: Who is he? Upon me is the covenant and pledge of Allah that I will not tell him (al-Hajjaj). He said: It was Ali bin Abi Talib (may Allah be pleased with him). Then he went in to al-Hajjaj and told him, and al-Hajjaj said: Woe to you, he has spoken the truth! We did not find fault with Ali (may Allah be pleased with him) for his judgements; we knew that Ali (may Allah be pleased with him) was the best judge among them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الدعوى والبينات / 21296