From Sahih Bukhari (Hadith 3900):
Narrated 'Ata bin Abi Rabah:`Ubaid bin `Umar Al-Laithi and I visited Aisha and asked her about the Hijra (i.e. migration), and she said, "Today there is no (Hijrah) emigration. A believer used to run away with his religion to Allah and His Apostle lest he should be put to trial because of his religion. Today Allah has made Islam triumphant, and today a believer can worship his Lord wherever he likes. But the deeds that are still rewardable (in place of emigration) are Jihad and good intentions." (See Hadith No. 42 Vol)
Reference: Bukhari 3900