Tobias has some hesitations (Tob 6:14-6:15)

“Then Tobias said in answer to Raphael.

‘Brother Azariah,

I have heard that she has been married to seven husbands.

Each one died in the bridal chamber.

On the night when they went in to her,

They would die.

I have people saying that it was a demon that killed them.

It does not harm her.

However, it kills anyone who desires to approach her.

Now, since I am the only son my father has,

I am afraid that I may die.

This would bring my father’s and mother’s life down to their grave, Grieving for me.

They have no other son to bury them.’”

I am not sure how Tobias had heard about the 7 dead husbands of Sarah. However, he was fearful that the same thing would happen to him. He too was an only child. If something happened to him, his parents would grieve so much that they might die. There would be no one to bury them since he had died.