Making a promise in itself is not sinful. But, if a promise is made and not fulfilled, then it is sin.
Matthew 5:37 teaches us to 'let our yes be 'yes', and our no be 'no'. If you make a promise, be sure to keep it. Be thoughtful when you make a promise. Make sure you have the power to keep it.
Ananya, I appreciate you here, your love for the Lord and desire to honor Him is wonderful. It's great to have you with us.