Sahih Muslim
The Book of Mosques and Places of Prayer
Hadith #271
5.271
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 " .
Abu Bakr reported on the authority of his father that the Messenger of Allah (ﷺ) said:He who observed two prayers at two cool (hours) would enter Paradise