Al-Matalib al-'Aliyah 3723 — Surah al-Hujurat

It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) used to pray two rak'ahs before Asr. (Once) a delegation of Banu al-Mustaliq came to him (peace and blessings be upon him). After the event (of the Battle of al-Muraysi'), he (peace and blessings be upon him) had sent al-Walid bin Uqbah to them to collect the zakah of their wealth. When Banu al-Mustaliq heard of his coming, some of them rode out (to receive him), saying: "We will greatly honour the envoy of the Messenger of Allah (peace and blessings be upon him), guide him through our lands and converse with him." But when al-Walid bin Uqbah heard of their coming, he turned back (out of some fear or misunderstanding) and came and said: "O Messenger of Allah! Banu al-Mustaliq have refused to pay their zakah." When those people learned that he had gone back, they too set out, following in his footsteps, until they reached Madinah. They joined the Messenger of Allah (peace and blessings be upon him) in the first row for the first prayer (Zuhr). When he (peace and blessings be upon him) concluded with the salam, they said (humbly): "We seek refuge with Allah and His Messenger from the anger of Allah and the anger of His Messenger." They kept apologising until the mu'adhdhin came for the Asr prayer. Then Allah Almighty revealed this blessed verse: "O you who believe! If a wicked person brings you news, verify it thoroughly, lest you harm a people out of ignorance and then become regretful over what you have done" [Surah al-Hujurat: 6].
In the chain of this report, Musa bin Ubaydah al-Rabadhi is a weak narrator; however, the origin of this event is found with other supporting reports in the books of tafsir and sirah, which explain the occasion of revelation of this verse.