Sayyiduna Abu Hurayrah (may Allah be pleased with him) says: A man was reviling Sayyiduna Abu Bakr (may Allah be pleased with him) while the Messenger of Allah (peace and blessings be upon him) was sitting there. He (peace and blessings be upon him) was showing amazement and smiling. When the man went on at length, Sayyiduna Abu Bakr (may Allah be pleased with him) answered him back, whereupon the Prophet (peace and blessings be upon him) became displeased and stood up. Sayyiduna Abu Bakr (may Allah be pleased with him) went after (him (peace and blessings be upon him)) and said: O Messenger of Allah (peace and blessings be upon him)! He was reviling me and you (peace and blessings be upon him) remained seated, but when I answered him, you (peace and blessings be upon him) became displeased and stood up. He (peace and blessings be upon him) said: "There was with you one (an angel) who was answering him; when you answered him, Satan sat down, and I do not sit with Satan." Then he said: "O Abu Bakr! No servant is wronged and bears it for the pleasure of Allah, except that Allah helps him and grants him honour."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 21096