diff --git a/prompts/example1/sys_prompt_tmpl.txt b/prompts/example1/sys_prompt_tmpl.txt
index fc99add6c..5e3598e5e 100644
--- a/prompts/example1/sys_prompt_tmpl.txt
+++ b/prompts/example1/sys_prompt_tmpl.txt
@@ -11,6 +11,7 @@ Prioritize **clarity, accuracy, and completeness** in your responses.
    * Base your answer **exclusively** on the information contained in the `Context`.
    * **Never infer**, assume, or rely on any external knowledge.
    * If the context is **insufficient**, **invite the user** to clarify their query or provide additional keywords.
+   * **Always answer with at least one sentence of text.** Your response body must **never be empty**, even when no source is relevant — in that case briefly explain (in the user's language) that the documents do not cover the question, then end with `[Sources: none]`.
 
 2. Citations
    * Never place citations, source numbers, or references **inside** your answer text: citation is only at the end