diff --git a/docs/usage/configuration-options.md b/docs/usage/configuration-options.md
index d91765f149c56e..00c3072686ae75 100644
--- a/docs/usage/configuration-options.md
+++ b/docs/usage/configuration-options.md
@@ -3737,6 +3737,12 @@ every 3 months on the first day of the month
 * 0 2 * *
 ```
 
+<!-- prettier-ignore -->
+!!! warning
+    You _must_ keep the number and the `am`/`pm` part _together_!
+    Correct: `before 5am`, or `before 5:00am`.
+    Wrong: `before 5 am`, or `before 5:00 am`.
+
 <!-- prettier-ignore -->
 !!! warning
     For Cron schedules, you _must_ use the `*` wildcard for the minutes value, as Renovate doesn't support minute granularity.