Muhammad bin al-Munkadir narrates from Sayyiduna Jabir (may Allah be pleased with him) that when the Messenger of Allah (peace and blessings be upon him) went up onto the minbar, he would give the greeting of salam.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5741
Nafi' narrates from Ibn Umar (may Allah be pleased with them both) that when the Messenger of Allah (peace and blessings be upon him) drew near the minbar on Friday, he would greet those sitting near it with salam; then, when he ascended the minbar, he would turn towards the people and give the salam.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5742
Nafi' (may Allah have mercy on him) mentions the like of it, but with these words: "When he (peace and blessings be upon him) ascended the minbar, he would greet the people with salam before sitting down."
Only Isa bin Abdullah bin al-Hakam bin al-Nu'man bin Bashir, Abu Musa al-Ansari, narrated it; Abu Ahmad bin Adi said: Most of what he narrates is not corroborated.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5743