See the Polytheists' Intentions

later on, the messenger of allâh [pbuh] dispatched ‘ali bin abi talib to trace them out. he said to him: "pursue them and see what they are going to do, and what they aim at. if they dismount horses and ride on camels’ back, this means that they are heading for makkah; but if they ride horses and lead camels unmounted, they are leaving for madinah. by the one, in whose hand my soul is, if they attacked madinah i would march to them there and i would fight them." ‘ali said: "i went out and traced them to see what they were up to. i saw them mounting camels and leaving the horses unmounted. they were heading for makkah." [ibn hisham 2/94]