Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: Sayyiduna Harithah bin al-Nu'man (may Allah be pleased with him) passed by the Messenger of Allah (peace and blessings be upon him) while Jibril (peace be upon him) was with him (peace and blessings be upon him), speaking privately with him, and he did not greet him with salam. Jibril (peace be upon him) said: What prevented him from greeting? Had he greeted, I would have returned his greeting. Then he said: Listen, he is one of those eighty Companions. The Messenger of Allah (peace and blessings be upon him) asked: "What are the eighty?" Jibril (peace be upon him) said: The people will flee from you except eighty, who will remain with you; their provision and the provision of their children is upon Allah in Paradise. Then when Harithah (may Allah be pleased with him) came back, he greeted with salam, and the Messenger of Allah (peace and blessings be upon him) said to him: "Why did you not greet when you passed by?" He said: I saw a person with you, and I disliked interrupting your conversation. He (peace and blessings be upon him) said: "Did you see him?" He said: Yes. He (peace and blessings be upon him) said: "That was Jibril (peace be upon him), and he said this," and then he (peace and blessings be upon him) told him what Jibril (peace be upon him) had said.
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3212