Speech acts like to pray, to swear or to make a prophecy include a transcendental participant to be felicitous. In a prayer the transcendental participant is included as interlocutor, in an oath as witness and, if necessary, punishing force, in a blessing as guarantor, and prophecy consists either in reporting the statements of a transcendental actor or a human speaker is making statements on his behalf. The illocution of a transcendental speech act is highly depend on introductory assumptions, especially sincerity. Accordingly, the linguistic classification of oath shifts between assertive and commissive speech acts. Our paper firstly discusses problems of the pragmatic classification of oaths in general; in a second step it is demonstrated, that the use of the Old Church Slavonic oath-formula „tako mi‟ and its descendants in Church Slavonic and in today’s oral speech are located within a pragmatic continuum between (transcendental) oath – extreme assertion – appellative request – emphatic salutation. The pragmatic classification of the formula is highly depend on register and substitution of the original 1st person pronoun (mi) by 2nd person pronoun (ti). Additionally, the paper offers a linguistic explanation about the original shape of the Old Church Slavonic formula in comparison with corresponding Greek utterances.