Language:
كتاب مواقيت الصلاة
9  
Times of the Prayers
(31)
Chapter: One should not try to offer As-Salat (the prayers) just before sunset
(31)
باب لاَ يَتَحَرَّى الصَّلاَةَ قَبْلَ غُرُوبِ الشَّمْسِ
Sahih al-Bukhari 587

Narrated Muawiya:

You offer a prayer which I did not see being offered by Allah's Messenger (ﷺ) when we were in his company and he certainly had forbidden it (i.e. two rak`at after the `Asr prayer).

حَدَّثَنَا مُحَمَّدُ بْنُ أَبَانَ، قَالَ حَدَّثَنَا غُنْدَرٌ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي التَّيَّاحِ، قَالَ سَمِعْتُ حُمْرَانَ بْنَ أَبَانَ، يُحَدِّثُ عَنْ مُعَاوِيَةَ، قَالَ إِنَّكُمْ لَتُصَلُّونَ صَلاَةً، لَقَدْ صَحِبْنَا رَسُولَ اللَّهِ صلى الله عليه وسلم فَمَا رَأَيْنَاهُ يُصَلِّيهَا، وَلَقَدْ نَهَى عَنْهُمَا، يَعْنِي الرَّكْعَتَيْنِ بَعْدَ الْعَصْرِ‏.‏
Reference : Sahih al-Bukhari 587
In-book reference : Book 9, Hadith 62
USC-MSA web (English) reference : Vol. 1, Book 10, Hadith 561
  (deprecated numbering scheme)