It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "The reward of performing Umrah in Ramadan is equal to that of Hajj."
Hadith Referenceمسند احمد / ومن مسند بني هاشم / 2808
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا سند ضعيف لسوء حفظ ابن أبى ليلى