Forbide write on table HTML

I have this code in HTML:

<table>       
    <tbody>
    <tr>
    <td contenteditable="true" id="a"> Texto1</td>
    <td contenteditable="true" id="b"> texto2</td>
    </tr>
   </tbody>
</table>

but I want to forbide users to write text in webpage over "Texto1" and "Texto2", but the users can change this. How can I forbide this?