Question 24: Every time I used to give birth to a baby boy, he would die. When I once gave birth to a baby boy, I vowed that if he lived, I would offer a yearly sacrifice on the 27th of Rajab, which is what people call Rajabiyyah. I then fulfilled the vow for years until I knew that this sacrifice is a Bid‘ah (innovation in religion). Now, I fear that my choice of this day may be sinful. Is it permissible for me to fulfill my vow on this day specifically or should I change it or there is nothing wrong with this? Please, advise. May Allaah reward you!
Answer: You must slaughter the animal and offer its meat to the poor and the needy each year as you vowed, out of gratitude to Allaah (Exalted be He)… read more here.