It is narrated from Nafi' (may Allah have mercy on him) that Ibn Umar (may Allah be pleased with him) performed Umrah several times in one year, and said this here twice.
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 782
Hadith Takhrijاسناده صحیح اخرجه البيهقی : 344/4 ۔ وفى المعرفة السنن والآثار له (2701)۔