Something to keep in mind -- a possible explanation regarding why there might be contradictions in the Quran and in the hadiths.

There is one possible explanation that readers should consider:  that Muhammad did not have the best memory, and in reciting his revelations from Allah, he forgot precisely what revelations he had said earlier, and unknowingly wound up contradicting earlier verses.  Muhammad himself declared that his memory was not perfect in this hadith told by Muhammad's wife, Aisha: "The Prophet (SAW) heard a man (reciting the Quran) in the Mosque, and he said, 'May Allah bestow His Mercy upon him. No doubt, he made me remember such-and such Verses of such-and-such Sura which I dropped (from my memory).'" [Sahih Bukhari, 3:823].