Sahih al-Bukhari 1183
Book 19: Prayer at Night (Tahajjud) · Narrated by `Abdullah Al-Muzani
Arabic
حَدَّثَنَا أَبُو مَعْمَرٍ، حَدَّثَنَا عَبْدُ الْوَارِثِ، عَنِ الْحُسَيْنِ، عَنِ ابْنِ بُرَيْدَةَ، قَالَ حَدَّثَنِي عَبْدُ اللَّهِ الْمُزَنِيُّ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " صَلُّوا قَبْلَ صَلاَةِ الْمَغْرِبِ ". ـ قَالَ فِي الثَّالِثَةِ ـ لِمَنْ شَاءَ كَرَاهِيَةَ أَنْ يَتَّخِذَهَا النَّاسُ سُنَّةً.
English translation
Narrated `Abdullah Al-Muzani:The Prophet (ﷺ) said, "Pray before the Maghrib (compulsory) prayer." He (said it thrice) and in the third time, he said, "Whoever wants to offer it can do so." He said so because he did not like the people to take it as a tradition
Reference: Sahih al-Bukhari 1183, Book of Prayer at Night (Tahajjud). English translation by Dr. Muhammad Muhsin Khan.