Al-Adab Al-Mufrad, Hadith 1170 ⓘ
Ibn 'Umar reported something similar from the Prophet, may Allah bless him and grant him peace. He stated, "We said, 'If there are four?' He said, 'Then it will not harm him.'"
وَحَدَّثَنِي أَبُو صَالِحٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم مِثْلَهُ، قُلْنَا: فَإِنْ كَانُوا أَرْبَعَةً؟ قَالَ: لا يَضُرُّهُ.
also referenced under: Book 47, Hadith 1170 (In-Book) & Book 47, Hadith 1170 (English)