Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
I am sorry I cannot figure out the precise intent of your question.
If you cursed yourself or invoked the curse of Allah on your child, etc. that is a grave sin; you ought to repent and ask forgiveness of Allah.
However, if you made a promise or pledge to do something that is not sinful, then you ought to fulfill it. Allah tells us that we ought to fulfill our commitments.
If, however, a person promises to do something that is displeasing to Allah, he or she should not do it. So, if you vowed to curse yourself or your child or anyone else, for that matter, then you are not allowed to carry it out.
Instead, you ought to seek forgiveness of Allah for uttering such words or intentions. Also, you should resolve never to repeat such mistakes in the future.
The Prophet, peace be upon him, said, “Whoever vows to do something good, let him fulfill the same; if however, he has vowed something sinful to do, he must never do it.” (Al-Bukhari)
If you can offer some charity by way of expiation, it would be highly desirable.
The Prophet, peace be upon him, said, “Charities wipe out sins.” Allah tells His messenger, “Take out from their wealth charities whereby you help them grow spiritually and purify them.” (Qur’an 9: 103)
Almighty Allah knows best.
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