It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) established brotherhood between Sayyiduna Abu al-Darda' and Sayyiduna Salman (may Allah be pleased with them both).
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 8053