Charles Ellicott Commentary Esther 5:14

"Then said Zeresh his wife and all his friends unto him, Let a gallows be made fifty cubits high, and in the morning speak thou unto the king that Mordecai may be hanged thereon: then go thou in merrily with the king unto the banquet. And the thing pleased Haman; and he caused the gallows to be made." — Esther 5:14 (ASV)

Gallows. —Literally, tree; the Hebrew word, as well as the corresponding Greek word used by the Septuagint, standing both for the living tree and the artificial structure. Doubtless, the punishment intended for Mordecai was crucifixion, as hanging, in the common sense of the term, does not seem to have been in use among the Persians. The same Hebrew word occurring above (Esther 2:23) is rendered tree. The Greek word employed is the same as that used in the New Testament for our Savior’s cross (Acts 5:30; Acts 10:39; and other similar passages). The Latin Vulgate here actually renders the word on its last occurrence as crucem.

Fifty cubits high. —That is, about seventy-five feet; the great height was intended to call as much attention as possible to the execution, so that Haman’s glory might be proportionately increased.