Sunnan Abu Dawud Collection: ::Book Number 14:: Hadith # 2519
Narrated AbuAyyub al-Ansari: AbuAyyub heard the Apostle of Allah (peace_be_upon_him) say: Capitals will be conquered at your hands, and you will have to raise companies in large armies. A man will be unwilling to join a company, so he will escape from his people and go round the tribes offering himself to them, saying: Whose place may I take in such and such expedition? Whose place may I take in such and such expedition? Beware: That man is a hireling to the last drop of his blood.