Sahih Bukhari Volume 4, Book 54, Hadith Number 443.

Narated By Ibn ‘Abbas : Allah’s Apostle was the most generous of all the people, and he used to be more generous in the month of Ramadan when Gabriel used to meet him. Gabriel used to meet him every night in Ramadan to study the Holy Quran carefully together. Allah’s Apostle used to become more generous than the fast wind when he met Gabriel.