Sahih al-Bukhari, Hadith 6951 ⓘ
Narrated `Abdullah bin `Umar: Allah's Messenger said, "A Muslim is a brother of another Muslim. So he should neither oppress him nor hand him over to an oppressor. And whoever fulfilled the needs of his brother, Allah will fulfill his needs."
حَدَّثَنَا يَحْيَى بْنُ بُكَيْرِ، حَدَّثَنَا اللَّيْثُ، عَنْ عُقَيْلٍ، عَنِ ابْنِ شِهَابٍ، أَنَّ سَالِمًا، أَخْبَرَهُ أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ ـ رضى الله عنهما ـ أَخْبَرَهُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " الْمُسْلِمُ أَخُو الْمُسْلِمِ، لاَ يَظْلِمُهُ، وَلاَ يُسْلِمُهُ، وَمَنْ كَانَ فِي حَاجَةِ أَخِيهِ، كَانَ اللَّهُ فِي حَاجَتِهِ " .
also referenced under: Book 89, Hadith 12 (In-Book) & Volume 9, Book 85, Hadith 83 (USC-MSA)