Sahl al-Fazari narrates from his father that Sayyiduna Jundub (may Allah be pleased with him) said: When the Messenger of Allah (peace and blessings be upon him) met his companions, he would not shake hands with them until he had greeted them with salam.
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1708