Abbott was recalled from Triple-A Rochester on Sunday, Mark Zuckerman of MASNSports.com reports.
Abbott was sent to Rochester on Aug. 20 but will rejoin the Nationals after spending the past few weeks in the minors. The right-hander has a 7.48 ERA across 27.2 frames in the big leagues this season, so he's likely to fill a low-leverage role out of the bullpen.