assure

Cause to feel sure; give reassurance to.

“The airline tried to reassure the customers that the planes were safe”

Be careful or certain to do something; make certain of something.

Make a promise or commitment.

Make certain of.

Inform positively and with certainty and confidence.

Assure somebody of the truth of something with the intention of giving the listener confidence.

“I assured him that traveling to Cambodia was safe”