It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) established brotherhood between Sayyiduna al-Zubayr and Sayyiduna Ibn Mas'ud (may Allah be pleased with them both).
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12761