From Sahih Bukhari (Hadith 3554):
Narrated Ibn `Abbas:The Prophet (ﷺ) was the most generous of all the people, and he used to become more generous in Ramadan when Gabriel met him. Gabriel used to meet him every night during Ramadan to revise the Qur'an with him. Allah's Messenger (ﷺ) then used to be more generous than the fast wind
Reference: Bukhari 3554