Qatadah (may Allah have mercy on him) mentions something similar, (saying) that a group of Arabs plotted to kill the Prophet (peace and blessings be upon him) treacherously, so they sent this Bedouin; then he recited this verse: "Remember the favour of Allah upon you when a people intended (to destroy you)." [Surah al-Ma'idah: 11]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18036