The bible permits, perhaps even encourages such a marriage. Abraham was not condemned for his marriage by G-d, so far as the Bible records. Rather, he was rewarded and his progeny became a great nation.
lol
Just because they did stuff in the Bible, doesn’t mean God endorsed it. Nobody mentioned in the old testament, even the prophets, were anything other than sinners as we all are. God even punished a lot of the old testament prophets.