blog/themes/classic/source/_includes/post_date.html

{% capture date %}{{ page.date }}{{ post.date }}{% endcapture %}
{% capture has_date %}{{ date | size }}{% endcapture %}
{% capture updated %}{{ page.updated }}{{ post.updated }}{% endcapture %}
{% capture was_updated %}{{ updated | size }}{% endcapture %}
{% if has_date != '0' %}
<time datetime="{{ date | datetime }}" pubdate {% if updated %} updated {% endif %}>{{ date | ordinalize }}</time>
{% endif %}
{% if was_updated != '0' %}
<time class="updated" datetime="{{ updated | datetime }}"></time>
{% endif %}