Sunan Ibn Majah, Volume 2, Book 5, Hadith 995 (DarusSalam) ⓘ
It was narrated that ‘Aishah said: “The Messenger of Allah said: ‘Allah and His angels send blessings upon those who complete the rows, and whoever fills a gap, Allah will raise him one degree in status thereby.’”
حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا إِسْمَاعِيلُ بْنُ عَيَّاشٍ، حَدَّثَنَا هِشَامُ بْنُ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " إِنَّ اللَّهَ وَمَلاَئِكَتَهُ يُصَلُّونَ عَلَى الَّذِينَ يَصِلُونَ الصُّفُوفَ وَمَنْ سَدَّ فُرْجَةً رَفَعَهُ اللَّهُ بِهَا دَرَجَةً " .
also referenced under: Hadith 995 (Reference) & Book 5, Hadith 1048 (In-Book)