When does the obligation to free a slave apply concerning necessary possessions?

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What is encompassed by a person's necessity is treated as non-existent, allowing transition to the substitute action (fasting), similar to finding water needed for thirst permitting transition to Tayammum. If one has a servant and is customarily served by them, freeing that servant is obligatory as it is surplus to need. This differs from one not accustomed to self-service, where freeing the servant causes hardship and wastage of necessities. If a slave serves the wife who requires service, or if one has slaves whose income supports him, a dwelling house, a property whose yield supports his sustenance, or goods for trade whose profit is necessary for sustenance, freeing a slave is not required. If one becomes free from any of these assets to the extent that he can purchase a slave with the remainder, freeing becomes obligatory, as he is now considered to have found a slave. If one possesses a slave who serves him, and he can sell that slave, buy two slaves with the price, use one for service, and free the other, it is obligatory, as there is no harm in this. Similarly, if one has luxurious clothing exceeding the standard for his peers, he can sell it, procure adequate clothing, and free a slave, and this is obligatory. If one has a house that can be sold to purchase a dwelling suitable for his peer's standard and a slave to free, or a farm from which the excess yield can purchase a slave, it is obligatory. The measure for what is considered surplus is that wealth which would disqualify one from receiving Zakat; if anything remains beyond that, the expiation becomes due. The view of Al-Shafi'i on this entire section aligns with what has been stated.