al-Haafidh ibn Rajab al-Hanbali al-Baghdaadi 795 AH, may Allah have mercy on him, said:

اعلم أن المؤمن يجتمع له في شهر رمضان جهادان لنفسه

جهاد بالنهار على الصيام و جهاد بالليل على القيام

فمن جمع بين هذين الجهادين و وفى بحقوقهما و صبر عليهما وفى أجره بغير حساب

“Know, that the believer in the month of Ramadan there are two struggles that gathered for him:

Struggling during the day with fasting and, struggling during the night with standing [in prayer].

Therefore, whoever gathered between these two struggles, fulfilled their rights, and were patient upon [implementing] them will be rewarded without reckoning.”

Source: Lataa’if al-Ma’aarif p. 171