Anytime you give your word you are bound by it. Our Guru is the Shabad Guru. Shabad is the power of the sound, which is the force that holds the Universe together. Whenever you give your word, especially in the presence of the Guru, you are bound by that. It is a vibration that you generate and which will never leave you. That is what being a Sikh is all about. If you are not prepared to honor your word, then don't give it. No one can force you. Once you give your word, though, God Himself will hold you to it. When you step from this life you will review all the sounds you created and their cause and effect and you will be held to those sounds you made, by your own soul.