240. He said to him: If so, "but on the first day you shall have put away leaven out of your houses" (Shemot 12:15). We have learned "but" sets a dividing line, meaning for a half day the eating of leaven is prohibited and for a half day it is permitted. It is also written here, "But on the tenth day of the month," meaning a half time forbidden to eat and a half time permitted. So He said to him here also, "And you shall afflict your souls." There is a separation, in that affliction takes place from midday onward, MEANING AFTER THE TIME ALLOTTED TO EATING. Thus "but" divides. This applies to "and you shall afflict your souls" as well.