Is what a father does by restricting food for his family, and contenting himself with very little of it, under the pretext of following the example of the Prophet (peace be upon him) who would only find dates and water for food, Islamically sound?

The maintenance of young children who have no wealth is obligatory upon the father by scholarly consensus, and it is considered among the best forms of charity. Refraining from obligatory maintenance is forbidden, and some scholars have counted it among the grave sins. The required maintenance is that which suffices them in a fair manner, and it is not fixed but rather depends on their need and circumstances. The father's argument for defaulting on maintenance by claiming he is emulating the Prophet, peace and blessings be upon him, is misplaced; because the Prophet, peace and blessings be upon him, did not refrain from spending out of miserliness, but rather due to the absence of anything to spend. The obligation of a parent's maintenance upon his child ceases when the child reaches maturity and has an income or wealth that makes him self-sufficient.