A woman vowed to name her son after one of the Companions but did not do so

Question:
The first remaining case is that I made a vow that if Allah granted me a child, I would name him after one of the Companions. When I gave birth to the child, I was unable to name him. I have given birth to eight children. Is there a sin on me for not fulfilling the vow, and what is its expiation? Knowing that my husband married a second woman and had a child from her, and he named the child with the name I wanted, saying that it was fulfillment of my vow. Is that sufficient?

Answer:
In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, and may Allah send prayers and blessings upon the Messenger of Allah, and upon his family and his Companions, and whoever follows his guidance. As for what follows, you must pay the expiation for an oath for your vow. It is not sufficient that your husband named [the child] after some of the Companions, because you are the one who made the vow. So you must pay the expiation for an oath, which is feeding ten poor people, or clothing ten of them, either lunch or dinner, or half a sa' (a dry measure of about 3 kg) of the staple food of the land, whether dates, rice, or wheat. This is what is obligatory. Or clothing each of them with a shirt or a lower garment or a cloak for your oath. Yes. May Allah reward you with good.