It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) set aside al-Naqi' as a protected pasture for the horses of the Muslims, "that they may graze in it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب إحياء الموات / 11808