Tafsir Ibn Kathir -> Surah Al-Baqarah -> The Virtue of Ramadan and the Revelation of the Qur'an in it.

Allah praised the month of Ramadan out of the other months by choosing it to send down the Glorious Qur'an, just as He did for all of the Divine Books He revealed to the Prophets. Imam Ahmad reported Wathilah bin Al-Asqa` that Allah's Messenger said:

«أُنْزِلَتْ صُحُفُ إِبْرَاهِيمَ فِي أَوَّلِ لَيْلَةٍ مِنْ رَمَضَانَ، وَأُنْزِلَتِ التَّوْرَاةُ لِسِتَ مَضَيْنَ مِنْ رَمَضَانَ، وَالْإِنْجِيلُ لِثَلاثَ عَشَرةَ خَلَتْ مِنْ رَمَضَانَ، وَأَنْزَلَ اللهُ الْقُرْآنَ لأَرْبَعٍ وَعِشْرِينَ خَلَتْ مِنْ رَمَضَان»

(The Suhuf (Pages) of Ibrahim were revealed during the first night of Ramadan. The Torah was revealed during the sixth night of Ramadan. The Injil was revealed during the thirteenth night of Ramadan. Allah revealed the Qur'an on the twenty-fourth night of Ramadan.)