He had heard it said since childhood:
Only God walks with the clouds.
Clouds were the sign of the divine—mystery, height, purity, distance.
If the Messiah was truly sent by God, then surely he too would come surrounded by such glory.
So the man prepared accordingly.
He washed himself with care, removing every trace of dust. He chose garments untouched by stain. He arranged his appearance so that nothing would be out of place. Even his thoughts he tried to purify.
Because one does not meet the divine in disorder.