"A person tends to follow the faith of his friend, so be careful who you make friends with" (Abu Dawud, Tirmidhi)
"On the day of Judgement you will be with those who you love." (Bukhari)
"He who is not trustworthy has no Faith, and he who does not keep his promise has no religion" (Baihaqi)
"The world is a prison for the believer, and a heaven for the disbeliever" (Muslim)