Midrash for Beitzah 29:17

(Devarim 16:8) "and on the seventh day is a holding back (atzereth) for the L-rd your G-d. You shall do no work." I might think that one should be "held back" all day long in the house of study; it is, therefore, written "a 'holding back' shall there be for you." How are the verses to be reconciled? Devote a portion to the house of study and devote a portion to eating and drinking.