The RAMBAM on SHMUEL (the Prophet Samuel)

B"H

Israel was commanded to fulfill the Mitzvot upon entering the Land:

1. To choose a king.

2. To wipe out the descendants of Amalek.

3. To build a Beit HaMikdash (G - d's chosen house).

Since it is a Mitzvah to appoint a king, why was G - d displeased with the people's request of a king from Samuel (Shmuel) ?

This is because they made their request in a spirit of complaint. Rather than seeking to fulfill the Mitzvah of appointing a king, they were simply intent on rejecting the Prophet Samuel (Shmuel).

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Source:

"Mishna Torah - Hilchot Melachim"

by the Rambam (Maimonides, 1135 - 1204)