If a person makes a vow to Allah (nazar) but does not fulfill it, what must that person do?

If a person makes a vow to Allah (nazar) but does not fulfill it, what must that person do?

If someone makes a vow to Allah but fails to fulfill it, they must pay the same kaffarah as for breaking an oath:

1.Feeding 10 poor people
2.If unable, fasting for three days

Reference (Hadith): “Whoever makes a vow but cannot fulfill it, must pay the kaffarah for breaking an oath.” (Narrated by Abu Dawud)