(Let not the believers take disbelievers for their friends in preference to believers…) [3:28].
Said Ibn 'Abbas: “A group of Jews including al-Hajjaj ibn 'Amr, Kahmas ibn Abi al-Huqayq and Qays ibn Zayd used to keep close company with a group of Helpers to try to make them renounce their religion. And so a group of people comprising Rifa'ah ibn al-Mundhir, 'Abd Allah ibn Jubayr and Sa'id ibn Khaythamah said to this group of Helpers: 'Stay away from these Jews and beware of keeping their company lest they drive you away from your religion'. The group of Helpers refused to stop seeing them or keep their company, and so Allah, exalted is He, revealed this verse”.
And al-Kalbi said: “This verse was revealed about the hypocrites: 'Abd Allah ibn Ubayy and his companions. They allied themselves with the Jews and the idolaters, supplying them with information, hoping that they would have the upper hand over the Messenger of Allah, Allah bless him and give him peace. And so Allah, exalted is He, revealed this verse, warning the believers against acting like them”.
Juwaybir reported from al-Dahhak that Ibn 'Abbas said: “This verse was revealed about 'Ubadah ibn al-Samit who was among those who took part in Badr and a trusted man. He had allies from among the Jews. And when the Prophet, Allah bless him and give him peace, marched to the Battle of the Confederates, 'Ubadah said: 'O Prophet of Allah! I have with me five hundred men from the Jews, and I am of the opinion to take them with me to impress the enemy. Because of this, Allah, exalted is He, revealed (Let not the believers take disbelievers for their friends in preference to believers)' ”.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou