Is it permissible to move the mosque's carpet to one's home for personal use if the mosque no longer needs it?

It is not permissible to benefit from the mosque's furnishings or any endowment specific to it outside the mosque, even if the mosque does not need them. In such a case, they should be transferred to another mosque. Any surplus from the endowment's revenue or anything no longer needed should be spent on a similar cause; thus, a surplus from the needs of one mosque should be spent on another mosque, because the intent of the endower is the same in kind. This is closer to the endower's objective, just as Ali (may Allah be pleased with him) spent the surplus wealth of a mukatab (slave who contracts for his freedom) on other mukatabun.