Sahih Muslim , Book 4, Hadith 1326 (USC-MSA) ⓘ
Abu Bakr reported on the authority of his father that the Messenger of Allah said: He who observed two prayers at two cool (hours) would enter Paradise.
وَحَدَّثَنَا هَدَّابُ بْنُ خَالِدٍ الأَزْدِيُّ، حَدَّثَنَا هَمَّامُ بْنُ يَحْيَى، حَدَّثَنِي أَبُو جَمْرَةَ الضُّبَعِيُّ، عَنْ أَبِي بَكْرٍ، عَنْ أَبِيهِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " مَنْ صَلَّى الْبَرْدَيْنِ دَخَلَ الْجَنَّةَ " .
also referenced under: Book 5, Hadith 274 (In-Book) & Hadith 635 (Reference)