Is it permissible for my mother to take the non-Muslim maid's cookbook, in which she recorded recipes that my mother taught her, on the pretext that she (my mother) was the one who taught her those recipes, and would that be considered an injustice to her?

Firstly: Bringing in non-Muslim female domestic workers poses a danger to the religion and morals of children. Scholars have warned against this, as the Arabian Peninsula is the cradle of Islam, and it is impermissible for two religions to coexist there except in cases of extreme necessity.

Secondly: It is permissible, according to Sharia, to take payment for teaching lawful worldly crafts and industries, such as cooking instruction. This is agreed upon by the Fiqh Encyclopedia.

Thirdly: Based on the above, your mother could have taken payment for teaching the domestic worker food recipes and preparation methods, provided the worker was informed of this beforehand. However, since the domestic worker learned purely by your mother's will, it is not permissible for her to take the domestic worker's notebook, as it is her property, and your mother's teaching is considered a donation. One must be careful not to oppress or subjugate the domestic worker, for Allah has forbidden injustice to His servants, even against disbelievers.