Albert Barnes Commentary Esther 5:4

"And Esther said, If it seem good unto the king, let the king and Haman come this day unto the banquet that I have prepared for him." — Esther 5:4 (ASV)

Esther seems to have been afraid to make her real request of Xerxes too abruptly. She concluded that the king would understand that she had a real petition in the background, and would return to it, as in fact he did (Esther 5:6; Esther 7:2).