It wasnarrated from Ibn 'Abbas that the Messenger of Allah (ﷺ)said:
"Whoever is in Makkah when the month of Ramadan comes, and hefastsit and prays at night as much as he can, Allah will record forhim(reward equivalent to that for) one hundred thousand months ofRamadan observed elsewhere. For each day Allah will record for him(reward equivalent to that for) freeing a slave, and for each day(reward equivalent to that for) providing a horse in the cause ofAllah, and for every day merits and for every night merits."
English reference: Vol. 4, Book 25, Hadith 3117
Arabic reference: Book 25, Hadith 3236