(bismillah) (salam) Adam's children married each other. That was because the law for Adam's family was incredibly simple compared to the message of Rasoolallah (saw). As the human population culturally evolved, Rasools, prophets of high status, came at different times to improve upon the rules of the past prophets. Prophet Yaqoob (as) had two wives whom were sisters of one another. By today's standards, this is haram, as it is forbidden to marry two sisters at the same time according to Shariah Law. However, this law did not apply in the time of Prophet Yaqoob (as). I have a question. To my knowledge, in the (original) Torah, Allah gave Bani Israel a set of laws which are more strict than the ones we have today. Does that mean Allah abrogates his own laws? It is well established that Shariah Laws can never change. Are the laws of the original Torah given to the Muslims under the leadership of Musa (as) considered Shariah? To my knowledge, the Injeel removed some of the crippling restrictions given to the Jews. Is this true? If this is true, then why would Allah enjoin laws which are crippling to begin with? Is each set of divine laws an addendum to last ones, adding new ones, or a destroyer and editor of past ones, removing them and changing them all together?