What are the restrictions on who may perform depilation on a person's private parts?

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A person must not allow anyone to remove hair from their private area except those whom it is permissible for to see that area, such as a wife or a female slave (ammah). Abu Abdullah (Ahmad ibn Hanbal) personally handled the application of Nura to his own pubic area, even when administered by others for the rest of his body. This practice of handling it personally is narrated regarding Ibn Umar, who would apply it himself to his own pubic area when Nafi applied it for him. It is reported that the Prophet (peace be upon him) did something similar.