How do you know?
I did find them, the author cites various pre-Islamic writers who documented peoples and towns founded by Ishmael's sons.
I think you're confused, Uriah was the soldier David set up to die in battle so he could have his wife - and of course it was sinful.
Now please answer the question: was God sinning when he gave David many wives or was David sinning for accepting the gift?
You stated, "if it is not the ideal it isn't sinning". Where is that statement in the bible?
It is when the brother accepting his brother's widow as his wife is already married.
Neither is bad or good, but wife stealing is bad
How do you know Ishmael's sons left no descendants who eventually converted to Islam?
Ishmael.
....
Snip 200 generations
Me.
Isn't that cool?!
But you've said not accepting it is less than ideal which you've defined as sin
Comment