Sunan Ibn Majah, Volume 5, Book 33, Hadith 3740 (DarusSalam) ⓘ
It was narrated that Anas said: "The Prophet used to come to us and say to a brother of mine, who was small: 'O Abu Umair.'".
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، عَنْ شُعْبَةَ، عَنْ أَبِي التَّيَّاحِ، عَنْ أَنَسٍ، قَالَ كَانَ النَّبِيُّ ـ صلى الله عليه وسلم ـ يَأْتِينَا فَيَقُولُ لأَخٍ لِي وَكَانَ صَغِيرًا " يَا أَبَا عُمَيْرٍ " .
also referenced under: Hadith 3740 (Reference) & Book 33, Hadith 85 (In-Book)