Muwatta Malik 514

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، أَنَّهُ قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏ "‏ إِذَا بَدَا حَاجِبُ الشَّمْسِ فَأَخِّرُوا الصَّلاَةَ حَتَّى تَبْرُزَ وَإِذَا غَابَ حَاجِبُ الشَّمْسِ فَأَخِّرُوا الصَّلاَةَ حَتَّى تَغِيبَ ‏"‏ ‏.‏

Yahya related to me from Malik from Hisham ibn Urwa that his father said that the Messenger of Allah, may Allah bless him and grant him peace, used to say, "Delay the prayer when the edge of the sun appears until it is completely in view, and delay the prayer when the edge of the sun is disappearing until it has completely disappeared

Reference

Muwatta Malik 514

In-book

Book 15, Hadith 45