It is narrated from Sayyiduna Zayd bin Arqam (may Allah be pleased with him); he said: I was with the Prophet (peace and blessings be upon him) when a man from the Jews came, who was called Tha'labah bin al-Harith, and he said: "As-salamu alayka (peace be upon you), O Muhammad!" He (peace and blessings be upon him) said: "Wa alaykum (and upon you)."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4995