What is the ruling on treachery in Islam, and is it permissible for the Messenger of Allah, may Allah bless him and grant him peace, to kill two men from the Jews treacherously?

The Prophet (peace and blessings be upon him) commanded the killing of Ka'b ibn al-Ashraf and Abu Rafi' Sallam ibn Abi al-Huqaiq because they violated the covenant, incited against Muslims, and carried out hostile acts. Their secret killing was a wise measure to avoid provoking the Jews who remained true to the covenant.