From Sahih Bukhari (Hadith 3220):
Narrated Ibn `Abbas:Allah's Messenger (ﷺ) 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 Qur'an carefully together. Allah's Messenger (ﷺ) used to become more generous than the fast wind when he met Gabriel
Reference: Bukhari 3220