Is it permissible to say “Wallah I will marry you” without saying In Shā’ Allāh

Swearing by Allah about something you will do in the future is permissible, and if you then do not do it you owe the expiation of an oath. If you attach in sha Allah to the oath immediately, Imam Ibn Baz said there is no breaking of the oath upon you, and Shaykh Ibn Uthaymin mentioned that some of the scholars require you to intend it as a condition and not merely as emphasis.