Is swearing by saying, "By God, that does not concern me, set its time whenever you wish," while internally disliking the matter, considered a laghw, mun'aqidah, or ghamus oath?

This oath is not a binding oath because it pertains to something already settled in the mind, which is indifference. It appears the questioner intended to emphasize her indifference to the appointment they would choose. Therefore, there is no sin upon her for the oath she uttered.