What is the legal ruling regarding a condition placed upon a marriage contract with a female slave specifying when she is delivered to the husband?

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If a condition is placed that the female slave is sent to the husband only at night for conjugal relations, the contract and the condition are valid. The husband is obligated to provide sustenance (nafaqah) for the duration she remains with him. The condition is valid because it does not violate the essential purpose of the marriage, as consummation only occurs at night. Consequently, the Nafaqah is due from the husband during the night because she has surrendered herself to him during that time. However, the husband owes no sustenance for the daytime, as this time corresponds to her service, which she cannot render to him while fulfilling the husband's right. Therefore, the daytime sustenance must be borne by the master, as she remains in his service, maintaining the original obligation upon the master. Likewise, the clothing allowance is divided between them.