What is the ruling on swearing by saying "InshaAllah" (God willing) with the intention of an oath, instead of "Wallahi" (by Allah), and does such an oath become binding?

This wording is not a form of oath, because an oath is only binding by swearing by Allah Almighty or by one of His attributes. It is not permissible to attach the will (mashiyah) to matters that have already occurred, because the exception relates to the future, not the past. Therefore, it is necessary to avoid attaching past matters to the will of Allah Almighty. So, if someone says: "By Allah, I did not do it, if Allah wills," after having done something, he has broken his oath.