אע"פ שאכל סעודה המפסקת מותר לחזור ולאכול אלא א"כ קבל עליו בפירוש שלא לאכול עוד היום הגה וקבלה בלב אינה קבלה אלא צריך להוציאו בשפתיו: (בית יוסף בשם התוס'):

1. Laws of the Parting Meal, which contains 2 paragraphs Even though one ate the Parting Meal, it is allowed to return and eat (more), unless one accepted upon himself explicitly not to eat further that day. Rema: Acceptance by thought is not an acceptance; rather, he needs to speak it with his lips (i.e. speak out the declaration) (Bais Yosef in the name of Tosafot)

2. The night of Tisha B'av is like the day in every matter, and we only eat while it is still day (i.e. on the eve of Tisha B'av). Twilight time (i.e. the time between certain day and certain night) is forbidden (to eat) like Yom Kippur. Rema:It is permitted to wash, anoint, wear shoes until Twilight. However in a weekday (Tisha B'av eve), we are accustomed to take off shoes before one says Barchu (beginning of Maariv of Tisha B'av); and if it is Shabbat, we take off our shoes after Barchu-- except for the prayer leader who takes them off before Barchu [Haagos Maimoni]-- so that we say hamavdil first (i.e. in the amidah before taking off our shoes so as to not do so before we have proclaimed the end of Shabbat) [Minhagim in the name of MaHaRack]. The custom is not to learn on the eve of Tisha B'av from Halachic Noon forward, except on matters allowed (to be learned) on Tisha B'av. Therefore if it (i.e. the eve of Tisha B'av) fell out on Shabbat, we do not say Pirkei Avot [Maharil and Minhagim]. Similarly, one should not travel on the eve of Tisha B'av.