Source: https://www.bertha-dudde.org/en/proclamation/7902
7902 Vows not in the will of God....
May 27, 1961: Book 82
What you want to achieve on earth you should achieve of your own free will but not feel induced to do so by coercion of any kind, for you should make a free decision of will and this alone determines your fate in eternity, your spiritual development, your spiritual maturity. And therefore you should not bind yourselves through a vow either, for then you will make your will unfree yourselves, and that does not correspond to My will. You will raise the objection that this vow was made by you of your own free will, but you should know that you are anticipating Me, that you are doing something for which you do not have My approval, which I would never give you either, precisely because of your freedom of will. You can do exactly the same thing you want to do even without having taken a vow, and then you will also be able to be certain of My blessing as soon as they are works of love.... But what good is a work which lacks love if you feel prompted to do such works by a spiritual compulsion?.... It will not take you one step further in your maturity of soul, and you will waste time which you could use better if you were free from any such obligation. You should not bind yourselves with a vow which I will never ever approve of, for every constraint kills, you render yourselves incapable of working with love.... because a constraint weighs down your soul and everything you do under this constraint cannot result in spiritual success. And that person who takes such a vow from you is also to be condemned, for he is controlled by My adversary, otherwise he would have to recognize the nonsensical, God-opposing nature which is expressed in a vow. You promise something and don't know whether you will be able to keep it, whether you will not break yourselves with such a vow, because you have completely wrong ideas if you believe that such a promise is pleasing to Me. For this reason no person should be of faith to make himself My servant through a vow if this is taken from him by a fellow human being.... As soon as he offers himself to Me Myself for service in My vineyard, as soon as he hands himself over to Me that I may accept him, his free will has become active and I then use him according to My will, where and how I need him. But a person should never take a vow from his fellow human being, and a person should never promise something if he himself does not know whether he will be able to keep it..... For then he will have relinquished his freedom of will, and his actions or omissions will be of no value, they will not be regarded as voluntary deeds in My eyes, as the individual's free decision of will. A vow can be the occasion for an activity which is then only carried out mechanically and whose value is thereby reduced. And a vow can also stifle any love that cannot be forced, that must come from the heart and also develop freely.... And only that which is based on love is pleasing to Me. It lets the soul mature and promotes development. And anyone who has love within himself does not need a vow.... he is driven from within to do everything, and he will truly always act as it is My will, as it pleases Me and as it is beneficial for his soul's salvation...._>Amen
Translated by Doris Boekers