The Messenger of Allah ﷺ said, "Whoever reaches Ramadan in Mecca and fasts and prays during it as much as he is able, Allah will record for him one hundred thousand Ramadans elsewhere. Allah will record for him for every day the freeing of a Raqaba, and for every night the freeing of a Raqaba, and for every day the provision of a horse for the cause of Allah, and for every day a good deed, and for every night a good deed."
حدثنا محمد بن أبي عمر العدني حدثنا عبد الرحيم بن زيد العمي عن أبيه عن سعيد بن جبير
قال رسول الله ﷺ من أدرك رمضان بمكة فصام وقام منه ما تيسر له كتب الله له مائة ألف شهر رمضان فيما سواها وكتب الله له بكل يوم عتق رقبة وكل ليلة عتق رقبة وكل يوم حملان فرس في سبيل الله وفي كل يوم حسنة وفي كل ليلة حسنة
No references are available.
[Its chain of transmission is extremely daif] Abu Naeem reported it in Akhbar Isbahan 2/196, through the hadith of Abdul-Raheem bin Zayd, in abridged form. See also number 2703 for its defect. Busiri graded it daif.