Abu Salama reported,

Regarding the man who passed by the Messenger of Allah ﷺ while he was speaking privately with Jibreel , Abu Salama claimed that the man avoided drawing near to the Messenger of Allah ﷺ, fearing that he might overhear his conversation.The next morning, the Messenger of Allah ﷺ said to him, "What kept you from greeting me with peace when you passed by me last night?"The man replied, "I saw you speaking privately with another man and feared you would dislike my coming close to the two of you."The Prophet ﷺ asked, "Do you know who that man was?"He answered, "No."The Prophet ﷺ said, "That was Jibreel . Had you greeted him with peace, he would have returned the greeting."I have also heard from someone other than Abu Salama that the man was Haritha bin Numan.

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أبو سلمة

عن الرجل الذي مر برسول الله ﷺ وهو يناجي جبريل عليه السلام فزعم أبو سلمة أنه تجنب أن يدنو من رسول الله ﷺ تخوفا أن يسمع حديثه فلما أصبح قال له رسول الله ﷺ ما منعك أن تسلم إذ مررت بي البارحة قال رأيتك تناجي رجلا فخشيت أن تكره أن أدنو منكما قال وهل تدري من الرجل قال لا قال فذلك جبريل عليه السلام ولو سلمت لرد السلام وقد سمعت من غير أبي سلمة أنه حارثة بن النعمان