Sahih Bukhari | Volume 8 | Hadith Number 431

Narrated by 'Utban bin Malik Al-Ansari
Who was one of the men of the tribe of Bani Salim: Allah's Apostle came to me and said, "If anybody comes on the Day of Resurrection who has said: La ilaha illal-lah, sincerely, with the intention to win Allah's Pleasure, Allah will make the Hell-Fire forbidden for him."