إِنَّهُ مَنْ قَامَ مَعَ الإِمَامِ يعنى في رمضان حَتَّى يَنْصَرِفَ كُتِبَ لَهُ قِيَامُ لَيْلَةٍ

Abu Dharr reported: The Messenger of Allah, peace and blessings be upon him, said, “Certainly, whoever stands for prayer in Ramadan with the Imam until he is finished, it will be recorded as if he prayed the entire night.”

Source: Sunan al-Tirmidhī 806 | Grade: Sahih (authentic) according to Al-Tirmidhi