Offering the Fajr Prayer in congregation then finding another person having missed the congregational Salah
It is permissible for
a person who has offered the Fajr Prayer in congregation and then sees a man who missed the congregation to offer Salah with him so that the latter may earn the reward of congregational Salah, and it is considered a Nafilah (supererogatory prayer) for the former, even if it is offered at a time when it is not permissible to offer supererogatory Salah. This is because it is a Salah offered for a reason. The more correct of the two opinions of scholars is that it is permissible during the times when supererogatory Salah is prohibited, based on the general meaning of the Hadith of the Prophet (peace be upon him),
“If you both already offered Salah at your places and then you came to a Masjid (mosque) where congregational Salah is held, pray with them too, for it will be a Nafilah for you.”
(Related by Imam
Ahmad and Ahl-ul-Sunan [Abu Dawud, Al-Tirmidhy, Al-Nasa’y and Ibn Majah]) The Prophet (peace be upon him) also told a man who entered the Masjid after the end of Salah,
“Is there any man who may do charity to this (man) and offer Salah with him?”
Abu Dawud) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.