To even suggest that a pure and pious prophet of God would be involved in such actions is disgraceful. To even mention pure, clean and supreme God would be involved with this is even more disgraceful! If it is disgraceful to marry your sister now, it was always been disgraceful to marry your sister. God would never allow this full stop! As mentioned before, God sent Hoors for the sons of Hazrat Adam (A.S.) and that is where the line of humans came from. This means that the next line of humans came from two cousins reproducing as is allowed today! This makes perfect sense. Think about it! God would never ever allow a brother and sister to marry each other! Islam has always been primarily the same from Hazrat Adam (A.S.) to Hazrat Mohammed S.A.W.W.) with minor changes for law bearing prophets. Islamic laws from Hazrat Adam (A.S.) to Hazrat Mohammed (S.A.W.W.) have always been pretty much the same!
It's a very good question you've asked. It may arise in a mind of a person who does not have a sound knowledge of History and Monotheist religions. When this world came into being. Adam was order to come in this world. There were no population at all.Hence it was allowed to them to marry their children with each other. But there is a very important point to remember. That the children who got married with each other were not belong to the same date of birth.
As if Eve gave birth of one son and one daughter in one turn. Then these both brother & sister would not marry with each other. But they would marry with their other siblings who were born in the next turn. And that was the rule for some specific period of time. And it has nothing to do with religion Islam. Because there were several things which were allowed in previous religion but later on they were not allowed in the next era of religion. Because the wisdom of humanity also developed with the passage of time. For example the prostration of respect was allowed earlier. But later on Islam didn't allow it. Similarly first there were no medical threats in the beginning. But afterwards it may cause some harm. That's why Almighty God who is Exalted in Might & Wisdom didn't allow it later on. For the benefit of humanity.
I really appreciate your question, Brother you are talking about a very early age when there were only two human beings ( HAZRAT ADAM & AMA HAWA) also called eve. Allah made this couple by his self and sent them to the earth for recreation. This was his law advised to HAZRAT ADAM that one child who will born in the morning can marry to another child who born in the evening. Keeping this very simple rule in his mind Hazrat Adman created couples and put them together under a contract called NIKAH or Marriage.
But after some time when so many couples were married and they reproduced there children this law was terminated. Now you can say this was the demand of that time. Otherwise there was no other option available to reproduce or re-product and grow. I hope I answer your question and satisfy your self that why at that time it was allowed to marry between sisters and brothers and why is it prohibited in our time. There is another angle of this question which you can ask to a doctor, why it is prohibited to not marry with your sisters and advised to marry out of your family.
First of all I know an alam. But I believe that its totally nonsense to say that Hazrat Adam (as) sons married to there on sister.Which does not make any sense. My question is if this is the case did it mention me from Quran or any ethantic hadith. This is totally blame worthy on Allah's Law. How can Allah allow first to get married with brother and sister and than he change the rule all of a sudden . When allah created them than allah send 2 hoor from janat so they can marry to each other and create a man kind.. So you also telling me that Hazrat adam and amma hawa both were brother and sister .. No allah does not creat such a thing..there is so many logical reason as well but this is what I believe.
Adam sons didnt marry to there own sister at all. And if thats the case than mention the sister name .Quran mention Habil and kabil.
One brother kill another one out of jealousy.but what about the sister..
Aoa,in early ages there was no marriage among siblings in the period of hazrat adam (a.s).the truth is that Allah create hazrat adam and hazrat hawa then he gave them kids in pairs one daughter and one son which are twins.Allah said to hazrat adam (a.s) in ko ik dosre ke behan bhaiyon se shadi karwao magar un me se ik apni behan se shadi karna chata tha because she is much beautiful to his brothers sis magar Allah ne unki apni behano ko ik dosrey pe haram kia ha or isi baat pe pehla qatal bhi hua...this the truth.