Abdullah bin al-Harith bin Nawfal (may Allah be pleased with him) said: I asked around in order to find someone who would tell me that the Messenger of Allah (peace and blessings be upon him) had offered a voluntary prayer while on a journey, but I found no one, until Umm Hani bint Abi Talib (may Allah be pleased with her) told me that on the day of the Conquest of Makkah he (peace and blessings be upon him) stood up and ordered a screen, so a screen was put up; he (peace and blessings be upon him) took a bath, then prayed eight rak'ahs of voluntary prayer.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21394