Hadith 17:399
Yahya ibn Adam narrated to us, from Hasan, from Mujalid, who said: He used to greet Umar by saying, "Peace be upon you, O Commander of the Faithful, peace be upon you," meaning upon those who were with him.
حدثنا يحيى بن آدم عن حسن عن مجالد قال كان يسلم على عمر السلام عليك يا أمير المؤمنين السلام عليكم يعني على من عنده