Can money paid to a relative suffering from kidney disease be counted as Zakat for wealth that has reached the Nisab, and is delaying the payment of Zakat considered a sin?

Zakat (definition) must be given when it becomes due, and it is not permissible to delay it except for a valid excuse or a recognized benefit. It is permissible to give it to a needy relative if you are not obligated to support them, and this is preferable, as the Prophet, peace and blessings be upon him, said: "Charity given to a poor person is one charity, but charity given to a relative is two: charity and strengthening ties." Zakat is not valid unless there is an intention to give it as zakat, and it is not sufficient if you intend it after it has been given.