The Prophet gave the land of Fadak to Fatima al-Zahra (as) under the order of Allah. This is proven from the following authority works of Ahl al-Sunnah:
Shawahid al-Tanzil. Vol. 1, pg. 338 - 441 by al-Hasakani
وَأخرج الْبَزَّار وَأَبُو يعلى وَابْن أبي حَاتِم وَابْن مرْدَوَيْه عَن أبي سعيد الْخُدْرِيّ رَضِي الله عَنهُ قَالَ: لما نزلت هَذِه الْآيَة {وَآت ذَا الْقُرْبَى حَقه} دَعَا رَسُول الله صلى الله عَلَيْهِ وَسلم فَاطِمَة فَأَعْطَاهَا فدك
Abu Sa’eed al-Khudri and Abdullah Ibn Abbas narrate that when the verse relating to giving rights to kindred was revealed, the Prophet called Fatima al-Zahra (as) and gifted the land of Fadak to her.