A Muslim Man raped his daughter-in-law. The Mullah then as per Quran asked the Man to marry his daughter-in-law.
No doubt - mohammed was great. He knew the sins of Islamist who would follow Koran and therefore had some special instructions for such case.
No doubt he gave legal right for marrying 4 Wives, he knew how insufficient the Islam Followers would be with one in the house. Hide and Hide - but out they tumble.