Hadith
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لاَ يَتَحَرَّ أَحَدُكُمْ فَيُصَلِّيَ عِنْدَ طُلُوعِ الشَّمْسِ وَلاَ عِنْدَ غُرُوبِهَا " .
Yahya related to me from Malik from Nafi from Abdullah ibn Umar that the Messenger of Allah, may Allah bless him and grant him peace, said, "You should not intend to pray either at sunrise or sunset
Sahih · Salim al-Hilali
Muwatta Malik 516 ·Book 15, Hadith 47·Also available on sunnah.com·