Mujahid (may Allah have mercy on him) says that the Messenger of Allah (peace and blessings be upon him) sent al-Walid bin Uqbah bin Abi Mu'ayt (may Allah be pleased with him) to Banu al-Mustaliq to collect the charity. They came to receive him with gifts, but he went back to the Messenger of Allah (peace and blessings be upon him) and said that Banu al-Mustaliq had resolved to kill you. So Allah Almighty revealed this verse: "O you who believe, if a wicked person brings you news, verify it carefully" [Surah al-Hujurat: 6].
The Shaykh said: What indicates that this happened a long time after the expedition against Banu al-Mustaliq, probably in the year 10 AH as Imam al-Shafi'i (may Allah have mercy on him) recorded, is that al-Walid bin Uqbah (may Allah be pleased with him) was a boy at the time of the Conquest of Makkah, which took place in the year 8 AH, and he (peace and blessings be upon him) would only send him (to collect charity) after he had become a grown man.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17976