(Exodus 12:16) "On the first day, a calling of holiness, etc.": Sanctify it with food and drink and with clean clothing. This tells me only that the first and last day of the festival are "callings of holiness." Whence do I derive the same for chol hamoed (the intermediate days)? From (Leviticus 23:38) "These (intermediate days) are the festivals of the L–rd, which you shall call callings of holiness."