diff --git a/docs/source/user-guide/sql/scalar_functions.md b/docs/source/user-guide/sql/scalar_functions.md
index c72ef94f42ea..50e1cbc3d622 100644
--- a/docs/source/user-guide/sql/scalar_functions.md
+++ b/docs/source/user-guide/sql/scalar_functions.md
@@ -1347,7 +1347,8 @@ date_bin(interval, expression, origin-timestamp)
 - **interval**: Bin interval.
 - **expression**: Time expression to operate on.
   Can be a constant, column, or function.
-- **timestamp**: Starting point used to determine bin boundaries.
+- **origin-timestamp**: Optional. Starting point used to determine bin boundaries. If not specified
+  defaults `1970-01-01T00:00:00Z` (the UNIX epoch in UTC).
 
 The following intervals are supported: