(Hast thou not observed those who were forbidden conspiracy…) [58:8].
Ibn 'Abbas and Mujahid said that this verse was revealed about the Jews and the hypocrites. This is because the latter used to talk secretly amongst themselves to the exclusion of the believers and then look at the believers and wink at each other. When the believers saw their secret communications, they said: “We think that they are doing this because they received news about our relatives and brothers who went out in military expeditions. They have been killed, wounded or defeated”. But when these secret conversations continued, they complained to the Messenger of Allah, Allah bless him and give him peace, and he commanded them not to speak in secret to the exclusion of the believers. They did not heed his command and went back to secret conversations among themselves. Allah, exalted is He, therefore revealed this verse.
(And when they come unto thee they greet thee with a greeting wherewith Allah greeteth thee not…) [58:8].
Abu Bakr Muhammad ibn 'Umar al-Khashshsab informed us> Abu Ishaq Ibrahim ibn 'Abd Allah al-Asfahani> Muhammad ibn Ishaq al-Sarraj> Qutaybah ibn Sa'id> Jarir> al-A'mash> Abu'l-Duha> Masruq> 'A'ishah who said: “Some Jews came to the Prophet, Allah bless him and give him peace, and said 'Al-Sam to you, O Abu'l-Qasim!' And so I replied: 'Al-Sam to you too, and may Allah take you away!' The Messenger of Allah, Allah bless him and give him peace, said: 'Stop, O 'A'ishah! For Allah, exalted is He, does not like indecency nor the uttering of indecent words'. I said: 'O Messenger of Allah, did you not hear what they said?' He said: 'Do you not see that I have sent back to them what they said. I said: the same to you'. This verse was revealed about this (And when they come unto thee they greet thee with a greeting wherewith Allah greeteth thee not)”.
Abu Sa'id Muhammad ibn 'Abd al-Rahman al-Ghazi informed us> Abu 'Amr Muhammad ibn Ahmad al-Hiri> Ahmad ibn 'Ali al-Muthanna> Zuhayr ibn Muhammad> Yunus ibn Muhammad> Shayban> Qatadah> Anas who said: “A Jewish man came to the Prophet, Allah bless him and give him peace, and said: 'Al-Sam be with you!' The people who were present responded to him with the greetings of peace. The Prophet, Allah bless him and give him peace, said to them: 'Do you know what this man said?' They said: 'O Prophet of Allah, Allah and His Messenger know best, [but we think he said: al-Salam [peace be with you]'. He said: 'No, rather he said such-and-such a thing. So drive it away from me'. They drove it away from him. He then asked the Jewish man: 'Did you say: al-Sam be with you?' He said: 'Yes, I did'. Upon which the Prophet of Allah, Allah bless him and give him peace, then said: 'When one of the people of the Book greets you, say to him in response: And the same to you'. Then the words of Allah, Allah exalted is He, revealed (And when they come unto thee they greet thee with a greeting wherewith Allah greeteth thee not)”.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou