Sunan an-Nasa'i, Volume 2, Book 19, Hadith 1597 (DarusSalam) ⓘ

It was narrated that Abu Hurairah said: "Umar came in when the Ethiopians were playing in the masjid. Umar, may Allah (SWT) be pleased with him, rebuked them, but the Messenger of Allah said: 'Let them be there, O Umar, for they are Banu Arfidah.'"

أَخْبَرَنَا إِسْحَاقُ بْنُ مُوسَى، قَالَ حَدَّثَنَا الْوَلِيدُ بْنُ مُسْلِمٍ، قَالَ حَدَّثَنَا الأَوْزَاعِيُّ، قَالَ حَدَّثَنِي الزُّهْرِيُّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ دَخَلَ عُمَرُ وَالْحَبَشَةُ يَلْعَبُونَ فِي الْمَسْجِدِ فَزَجَرَهُمْ عُمَرُ رضى الله عنه فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ دَعْهُمْ يَا عُمَرُ فَإِنَّمَا هُمْ بَنُو أَرْفِدَةَ ‏" ‏ ‏.‏