I can assure you of the reliability of the information.
The captain of the ship assured the passengers that there was no danger.
We assured our clients of an enjoyable holiday.
They assured themselves that the bridge was safe before crossing it.
Her future was assured.
I can't ensure his being on time.
I can't ensure that he will be there on time.
This medicine will ensure you a good night's sleep.
These are safety devices to ensure workers against accidents.