Rashi on Numbers 22:19/רש"י על במדבר כ״ב:י״ט

1גם אתם [ABIDE] ALSO YE [HERE] — His mouth tripped him up (unwittingly he spoke the truth): you also in the end will go away disappointed as the former princes (Midrash Tanchuma, Balak 6).

2מה יסף WHAT MORE [THE LORD WILL SAY TO ME] — He certainly will not change His words from a blessing to a curse: I only hope that he will not add a further blessing. — He here prophesied that He would in the end give them a further blessing by his agency (Midrash Tanchuma, Balak 6).