What is the ruling on a man saying "by trustworthiness such and such," when he does not intend thereby to swear an oath, but rather means that he is speaking truthfully?

If the one swearing by the word "by trust" (بالأمانة) did not intend to swear by other than Allah, but rather meant to entrust the مخاطَب (the addressed person) to tell him the truth, then there is no harm in it. However, it is preferable to avoid this style. But if he intended to swear by the trust, then it is an oath by other than Allah, and this is minor shirk (polytheism) and one of the greatest major sins, because the Prophet, peace and blessings be upon him, said: "Whoever swears by other than Allah has disbelieved or committed shirk," and "Whoever swears by trust is not of us."