Yours, Etc.: Origins and Uses of 8 Sign-Offs
Old English wiðstandan, from wið "against" (see with) + standan "to stand" (see stand (v.)); perhaps a loan-translation of Latin resistere "to resist" (see resist). Cf. Old Norse viðstanda, Old Frisian withstonda, Old High German widarstan. In 14c. and early 15c., withsit was in use with the same meaning. Related: Withstood; withstanding.