What is the meaning of "his sleeping past the Qur'an" in the hadith about the punishment for one who misses prayer, and is reading the Qur'an at night obligatory?

The hadith referred to is: "As for the one whose head is crushed with a stone, he is the one who takes the Qur'an but then rejects it, and sleeps through the obligatory prayers," narrated by Al-Bukhari. The hadith does not mention sleeping through the Qur'an; rather, it warns against sleeping through the obligatory prayers and against rejecting the Qur'an by abandoning its memorization and practice. Reciting the Qur'an at night is not obligatory; it is a recommended Sunnah, and there is no sin upon one who sleeps through it, but he misses out on a great reward.