The following morning, when news of this pledge began spreading in Makkah, the Quraish came to the Ansaar to verify this news. Since there were some disbelievers and idol-worshippers in this caravan as well, and they had no knowledge whatsoever of this pledge, they rejected it saying, “This information is completely incorrect. If it was true, we would have definitely known about it.”
After some time, this caravan, comprising of Muslims and non-Muslims alike, departed for Madinah. It was only after they had departed that the Quraish learnt that the information they received about this pledge was authentic. They swiftly despatched some people to give chase and apprehend the caravan, but the caravan had already covered some distance and they were unable to catch up.
They only managed to seize Hazrat Sa’d bin ‘Ubaadah (radhiyallahu ‘anhu) who was left behind the caravan. They captured him on the road and subjected him to a severe beating. Jubair bin Mut’im (radhiyallahu ‘anhu) then came and managed to rescue him from their clutches.
(Extracted from Seeratul Mustafa 1/344-345)