How to Restrict Numbers in a Single Line Text Form Field

/**

 * Disallow numbers in a single-line text field

 *

 * @link https://wpforms.com/developers/how-to-restrict-numbers-in-a-single-line-text-form-field/

 */

function wpf_dev_disallow_numbers_text_field( $fields, $entry, $form_data ) {

    // Optional, you can limit to specific forms. Below, we restrict output to

    // form ID #1000.

    if ( absint( $form_data[ 'id' ] ) !== 1000 ) {

        return $fields;

    }

    // get value of the specific field ID and set it to a variable

    // field ID #25

    $mystring = $fields[25][ 'value' ];

    if (!preg_match ('/^([a-zA-Z]+)$/', $mystring))  

      {

        // Check the field ID 25 and show error message at the top of form and under the specific field

        wpforms()->process->errors[ $form_data[ 'id' ] ] [ '25' ] = esc_html__( 'The username can only contain letters.', 'plugin-domain' );

      }

}

add_action( 'wpforms_process', 'wpf_dev_disallow_numbers_text_field', 10, 3 );