If someone is unsure whether they have fulfilled a religious obligation, they can:

1. **Review Knowledge**: Revisit the requirements of the obligation to confirm what is necessary.

2. **Consult a Scholar**: Seek guidance from a knowledgeable person or scholar to clarify any doubts.

3. **Repeat if Necessary**: If the obligation is easy to repeat and there’s doubt, it may be best to fulfill it again for certainty.

4. **Make Dua for Forgiveness**: Ask Allah for forgiveness and guidance if unsure.

These steps help ensure religious duties are properly fulfilled.