Is it obligatory to pay zakat on half a million Egyptian pounds found after the death of the mother, knowing that she only used to pay 10,0 pounds of her zakat, and how is zakat calculated for 37 years, considering that the money accumulated gradually?

If the heirs are certain that their mother did not pay zakat, it is obligatory to pay it from the capital, for the rights of Allah take precedence over the rights of human beings. This is based on the saying of the Prophet (PBUH): "The debt owed to Allah is more deserving of being fulfilled." Some scholars, however, hold the view that the heirs are not obliged to pay it if the deceased did not make a will concerning it. If they are not certain but there are indications that it was not paid, then it is safer to pay it with the consent of the adult heirs. The share of the minor or the one who refuses should be given in full. It is necessary to strive to determine the years in which the wealth reached the nisab and the amount of zakat for each year, and to pay it to the best of one's ability, as Allah says: "Allah does not burden a soul beyond its capacity."