Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) said: When the Messenger of Allah (peace and blessings be upon him) was in the valley called al-Aqiq, I heard him (peace and blessings be upon him) say: "Tonight a visitor came to me from my Lord and said: Pray in this blessed valley, and say that Umrah is (included) within Hajj."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 8849