Abu Jurayy reported,
I saw a man whom people were turning to for his opinion. He would not say anything except that they accepted it from him.I asked, "Who is this?"They said, "This is the Messenger of Allah ﷺ."I said, "Upon you be peace, Messenger of Allah," twice.He said, "Do not say, 'Upon you be peace,' for 'Upon you be peace' is the greeting of the dead. Say instead, 'Peace be upon you.'"I said, "Are you the Messenger of Allah?"He replied, "I am the Messenger of Allah, the One whom, if harm befalls you and you call upon Him, He removes it from you. If a year of drought afflicts you and you call upon Him, He causes growth for you. And if you are in a barren land or open wilderness and your mount goes astray, and you call upon Him, He returns it to you."I said, "Give me some counsel."He said, "Do not insult anyone."After that, I never insulted any free person, slave, camel, or sheep.He continued, "Do not belittle any act of kindness, and that you speak to your brother with a cheerful face is itself an act of kindness. Raise your lower garment to mid-calf, and if you refuse, then to the ankles, and beware of letting your garment trail, for that comes from arrogance, and Allah does not love arrogance. If a man insults you and reproaches you with something he knows about you, do not reproach him with what you know about him, for the consequence of that falls upon him."
Azami 14240
Sahihعن أبي جري جابر بن سليم، قال
رأيت رجلا يصدرالناس عن رأيه، لا يقول شيئا إلا صدروا عنه، قلت: من هذا؟ قالوا: هذا رسول الله ﷺ، قالت: عليك السلام يا رسول الله، مرتين، قال: لاتقل: عليك السلام، فإن عليك السلام تحية الميت، قل: السلام عليك قال: قلت: أنت رسول الله؟ قال: أنا رسول الله الذي إذا أصابك ضرفدعوته كشفه عنك، وإن أصابك عام سنة فدعوته، أنبتها لك، وإذا كنت بأرض قفراء- أو فلاة- فضلت راحلتك فدعوته، ردها عليك، قال: قلت: اعهد إلي، قال: لا تسبن أحدا قال: فما سببت بعده حرا، ولا عبدا، ولا بعيرا، ولا شاة، قال: ولا تحقرن شيئا من المعروف، وأن تكلم أخاك وأنت منبسط إليه وجهك إن ذلك من المعروف، وارفع إزارك إلى نصف الساق، فإن أبيت فإلى الكعبين، وإياك وإسبال الإزار، فإنها من المخيلة، وإن الله لا يحب المخيلة، وإن امرؤ شتمك وعيرك بما يعلم فيك، فلا تعيره بما تعلم فيه، فإنما وبال ذلك عليه.
Abu Dawud (4084) narrated it, and the wording is his, as did Tirmidhi (2722) and Bayhaqi in Shuab (5730), all of them from the hadith of Abu Ghifar Muthanna bin Saeed Tai, from Abu Tamima Hujaymi, from Jabir bin Sulaym, who related it. Tirmidhi said, "This is a hasan sahih hadith." Hakim (4/186) graded it sahih. Ahmad (20635) reported something similar, both of these coming through Abu Tamima Hujaymi, from Jabir, with similar wording.Ahmad (16616) also narrated it through Khalid Haddan, from Abu Tamima, and in it the man asked, saying, "What do you call people to?" He said, "I call to Allah 
alone." The discussion of this is set out at length in the Book of Clothing.As for his saying, "Upon you be peace, the greeting of the dead," Khattabi said, "This gives the impression that the sunnah for greeting the dead is to say to him, 'Upon you be peace,' as many common people do. Yet it has been established from the Prophet ﷺ that he entered the graveyard and said, 'Peace be upon you, people of this abode who are believers,' placing the supplication before the name of the one being addressed, just as is done in the greeting of the living. He only spoke that other phrase in reference to what was customary among them in greeting the dead, since they used to place the name of the deceased before the supplication. This is found in their poetry, as in the poet's line,Upon you be the peace of Allah, Qays bin Asim, and His mercy, as much as He wills to show mercy,and as in the saying of Shammakh,Upon you be peace from a tanned hide, and Allah's hand has blessed that torn hide.So the sunnah does not differ between the greeting of the living and the greeting of the dead." End of quote.