What is the ruling on equal division of time between a free woman and a slave woman (ammah)?

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Ali ibn Abi Talib, Sa'id ibn al-Musayyab, Masruq, Shafi'i, Ishaq, and Abu 'Ubayd hold that the division between a free woman and a slave woman is unequal; the slave receives one night and the free woman receives two. Abu 'Ubayd reported this as the madhhab of Thawri, Awza'i, and the People of Opinion (Ahl al-Ra'y). Malik, in one narration from him, held that the free woman and the slave woman should be equal in the division because they are equal in marriage rights regarding maintenance, lodging, and initial division. Our evidence is the narration from Ali (RA) that when a free woman is married over a slave woman, the slave receives one night and the free woman two, which Ahmad used as proof. The free woman must be handed over day and night, so her share in lodging should be greater. This differs from maintenance and lodging, which are estimated by need, and the need of the slave woman is like that of the free woman. The initial division was legislated so that reserve would cease between them, and they are equal in that respect, thus they should be divided equally in our case.