It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) used to offer voluntary prayer on the mount, whichever direction his face was turned, and he would also pray witr on it; however, he did not offer the obligatory prayer on the mount.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2218