Is the amount designated for the sacrifice after paying off debt and the son's recovery (3,000 to 4,000 EGP) to be allocated solely for the sacrifice, or is it permissible to give a portion of it to the poor and a portion to a cancer hospital?

Whoever vows to slaughter an animal for the sake of Allah Almighty to feed its meat, must fulfill what he vowed. It is not permissible for him to pay its price to the poor or to the hospital. If he finds an animal at a cheaper price, he may donate the difference.