The Prophet ﷺ gave a third as additional reward after the fifth had been set aside.
حدثنا يحيى بن سعيد عن سعيد بن عبد العزيز حدثنا مكحول عن زياد بن جارية
أن النبي ﷺ نفل الثلث بعد الخمس
No references are available.
Its isnad is sahih, and Saeed bin Abdul-Aziz is a trustworthy and firmly reliable narrator, praised by Ahmad, as will come at the end of these hadiths.