Sahih Bukhari, Chapter: Funerals (Al-Janaaiz)

The Prophet (p.b.u.h) said, "Whoever intentionally swears falsely by a religion other than Islam, then he is what he has said, (e.g. if he says, 'If such thing is not true then I am a Jew,' he is really a Jew). And whoever commits suicide with piece of iron will be punished with the same piece of iron in the Hell Fire." Narrated Jundab the Prophet said, "A man was inflicted with wounds and he committed suicide, and so Allah said: My slave has caused death on himself hurriedly, so I forbid Paradise for him."