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