The Jews used to say to the Messenger of Allah ﷺ, "Sam alayka," and then they would say among themselves... So this verse was revealed, "And when they come to you, they greet you with that with which Allah does not greet you" [Mujadila 58:8], to the end of the verse.
أن اليهود كانوا يقولون لرسول الله ﷺ: سام عليك، ثم يقولون في أنفسهم: فنزلت هذه الآية: {وإذا جاءوك حيوك بما لم يحيك به الله} إلى آخر الآية.
Ahmad (6589), Bazzar (Kashf Astar 3/75), and Bayhaqi in Shuab al-Iman (8679) all narrated it through Hammad bin Salama, from Ata bin Saaib, from his father, from Abdullah bin Amr, who mentioned it.Ata bin Saaib is reliable, and a group of scholars affirmed his reliability, except that his memory became confused toward the end of his life. Hammad bin Salama is among those who heard from him before this confusion set in.Haythami said in Majma (7/121–122), "Its chain of transmission is good."