How do i select the preceding nodes of a text node starting from a specific node whose id i know instead of getting the text nodes from the root node?

When i invoke the below piece from a template match of text node, I get all the preceding text nodes from the root. I want to modify the above piece of code to select only the text nodes that appear after the node having a specific id say 123. i.e something like //*[@id='123']

          <xsl:template match="text()[. is $text-to-split]"> 
          <xsl:variable name="split-index" as="xsd:integer" 
           select="$index - sum(preceding::text()/string-length(.))"/> 
          <xsl:value-of select="substring(., 1, $split-index - 1)"/> 
          <xsl:copy-of select="$new"/> 
          <xsl:value-of select="substring(., $split-index)"/> 
          </xsl:template> 

         <xsl:variable name="text-to-split" as="text()?" 
         select="descendant::text()[sum((preceding::text(), .)/string-length(.)) ge $index][1]"/> 

How do i include the condition in places where i use preceding::text inorder to select preceding text nodes relative to the specific node's id which i know?