From Sahih Muslim (Hadith 3365):
Sufyan b. Abu Zuhair heard Allah's Messenger (ﷺ) say:Yemen will be conquered and some people will go away (to that country) driving their camels and carrying their families on them and those who are under their authority, while Medina is better for them if they were to know it. Then Syria will be conquered and some people will go away driving their camels along with them and carrying their families with them and those who are under their authority, while Medina is better for theni if they were to know it. Thtn lraq will be conquered and some people will go away (to that country) driving their camels and carrying their families with them and those who are under their authority. while Medina is better for them if they were to know it
Reference: Muslim 3365