Sahih Bukhari Volume 4, Book 56, Hadith Number 792.

Narated By Abu Said Al-Khudri : The Prophet said, “A time will come when the people will wage holy war, and it will be asked, ‘Is there any amongst you who has enjoyed the company of Allah’s Apostle?’ They will say: ‘Yes.’ And then victory will be bestowed upon them. They will wage holy war again, and it will be asked: ‘Is there any among you who has enjoyed the company of the companions of Allah’s Apostle ?’ They will say: ‘Yes.’ And then victory will be bestowed on them.”