The Messenger of Allah ﷺ used to give an extra share to some members of the expeditions he dispatched, set aside specifically for them apart from the general distribution of spoils to the army, and the fifth was still due in full from all of it.
أن رسول الله ﷺ قد كان ينقل بعض من يبعث من السرايا لأنفسهم خاصة سوى قسم عامة الجيش، والخمس في ذلك واجب كله.
Bukhari narrated it in the chapter on the obligation of the khumus (3135), and Muslim in the chapter on jihad and expeditions (1750:40), both of them through Layth, who said, Aqeel bin Khalid told me, from Ibn Shihab, from Salim, from Ibn Umar, and he related it. The wording given is Muslim's, and Bukhari does not include his statement, "and the khumus is entirely obligatory in that."