Yahya related to me from Malik that Yahya ibn Said used to hearSaid ibn al-Musayyab say, "Anyone that does umra in Shawwal,Dhu'l-Qada or Dhu l-Hijja, and then stays in Makka until it is timefor the hajj, is doing tamattu if he then does hajj. He must sacrificewhatever animal it is easy for him to obtain, and if he cannot findone then he must fast three days during hajj and seven days when hereturns."
USC-MSA web (English) reference: Book 20, Hadith 64
Arabic reference: Book 20, Hadith 769