Parshas Hashavua                                     מלאכים ממש  Kabbalists  had a  practice of  forcing an oath on the Angels   ( משביעין את המלאכים ). "Hashem gives permission to the מלאכים to do as they are commanded (by humans) even if the recipients  are  not worthy and have no זכויות in their favour". (Levush)  There used to be a Minhag for Chazanim to force an oath on the מלאכים.The Chazanim were concerned, an עין הרע will cause them to lose their voice during Davening.    The Chazanim had a Nusach they said, before saying המלך.(Yomim Noroim) בשם שמעי' -------(שמות של מלאכים)---- אני פלוני בן פלוני משביע אני עליכם   שתסייעו לי שאתפלל היום בקול רם ונעים וערב ואל יחר גרוני ואל ילאה רוחי וכוחי (In the name of the Malochim --- I Ploni the son of Ploni, place a Shevuah on you (מלאכים) that you will help me to Daven today with a voice that is loud, pleasant  and sweet, and my throat shouldn’t anger (cough) and my spirit and strength shouldn’t tire.)   The Levush (O.Ch.584) was against this השבעה (oath). He claims it is wrong to force Hashem to accept your Tefillos. The acceptance of Tefillos is dependant on the כוונת הלב, and you may not force it. The second issue the Levush had against it, was, Hefsek, The Nusach was said after ברוך שאמר.(before Hamelech) The Levush suggest to eliminate it altogether and if not possible, then it should be said before ברוך שאמר.   * loss of voice would be a sign of non acceptance of Tefilos