A student of the baal shem tov – saw a fellow talmid – student praying on Yom Kippur. The student – feeling weak – pulled out a box of tobacco snuff to take a sniff. Noticing the gesture, he looked at the act with derision. “on one of the holiest days of the year he is looking to sniff tobacco?” he thought.
The baal shem tov took note of this. The student was studying one day before him. He prayed that he would be distracted. Distracted, the student could not concentrate. He tried to concentrate to no avail. Finally he took out his snuff box and took a sniff. He realized his distraction was due to his derision of the other talmid on Yom Kippur. He did teshuva – repented for his lack of judging favorably and was able to concentrate again.