Abu Hurayra reported that the Messenger of Allah, may Allah bless him and grant him peace, said, “What is the most frequent reason for someone entering Paradise?” He said, “Taqwa and good character. He was asked, “What is the most frequent reason for people entering the Hellfire?” He replied, “The two empty ones:
the mouth and the genitals.”
حَدَّثَنَا مُحَمَّدُ بْنُ سَلاَمٍ، عَنِ ابْنِ إِدْرِيسَ قَالَ‏:‏ سَمِعْتُ أَبِي يُحَدِّثُ عَنْ جَدِّي، عَنْ أَبِي هُرَيْرَةَ‏:‏ سُئِلَ رَسُولُ اللهِ صلى الله عليه وسلم‏:‏ مَا أَكْثَرُ مَا يُدْخِلُ الْجَنَّةَ‏؟‏ قَالَ‏:‏ تَقْوَى اللهِ، وَحُسْنُ الْخُلُقِ، قَالَ‏:‏ وَمَا أَكْثَرُ مَا يُدْخِلُ النَّارَ‏؟‏ قَالَ‏:‏ الأَجْوَفَانِ‏:‏ الْفَمُ وَالْفَرْجُ‏.‏
Arabic/English book reference : Book 14, Hadith 294