Esther 2:14

2:14 In the evening she went, and in the morning she returned to a separate part of the harem, to the authority of Shaashgaz the king’s eunuch who was overseeing the concubines. She would not go back to the king unless the king was pleased with her and she was requested by name.

Esther 5:14

5:14 Haman’s wife Zeresh and all his friends said to him, “Have a gallows seventy-five feet high built, and in the morning tell the king that Mordecai should be hanged on it. Then go with the king to the banquet contented.”

It seemed like a good idea to Haman, so he had the gallows built.