Hadith 507630
Chapter 20: Hajj - كتاب الحج
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ حَرْمَلَةَ الأَسْلَمِيِّ، أَنَّ رَجُلاً، سَأَلَ سَعِيدَ بْنَ الْمُسَيَّبِ فَقَالَ أَعْتَمِرُ قَبْلَ أَنْ أَحُجَّ، فَقَالَ سَعِيدٌ نَعَمْ قَدِ اعْتَمَرَ رَسُولُ اللَّهِ صلى الله عليه وسلم قَبْلَ أَنْ يَحُجَّ .
Yahya related to me from Malik, from Abd ar-Rahman ibn Harmala al-Aslami, that somebody asked Said ibn al-Musayyab, "Can I do umra before I do hajj?", and Said said, "Yes, the Messenger of Allah, may Allah bless him and grant him peace, did umra before doing hajj."
Reference Muwatta Malik 507630
USC-MSA web (English) reference : Book 20, Hadith 58