What is the ruling of Islamic law on swearing by the Qur’an not to leak secrets and to serve the community with sincerity and honesty?

It is not permissible to disclose a entrusted secret, based on the Prophet, peace and blessings be upon him, saying: "If a man tells you something, then turns around, it is a trust." It is a betrayal to disclose a brother's secret. Preserving secrets is strongly enjoined by Islamic law. Therefore, there is no objection for each of you to swear an oath on the Qur'an not to reveal your secret; this further emphasizes the preservation of the secret. Similarly, an oath can be taken to serve the group. Your association must be free from any Sharia prohibitions, and the secret that needs to be concealed must not contain any Sharia prohibition, nor should its concealment involve any such prohibition.