It is narrated from Sayyiduna Suraqah bin Malik bin Ju'shum (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Behold! Umrah has entered into Hajj until the Day of Resurrection."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6565