Sahih al-Bukhari, Volume 2, Book 26, Hadith 729 (USC-MSA) ⓘ

Narrated Nafi`: `Abdullah bin `Umar used to offer the Maghrib and `Isha' prayers together at Jam' (Al-Muzdalifa). But he used to pass by that mountain pass where Allah's Messenger went, and he would enter it and answer the call of nature and perform ablution, and would not offer any prayer till he had prayed at Jam.'

حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا جُوَيْرِيَةُ، عَنْ نَافِعٍ، قَالَ كَانَ عَبْدُ اللَّهِ بْنُ عُمَرَ ـ رضى الله عنهما ـ يَجْمَعُ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ، غَيْرَ أَنَّهُ يَمُرُّ بِالشِّعْبِ الَّذِي أَخَذَهُ رَسُولُ اللَّهِ صلى الله عليه وسلم فَيَدْخُلُ فَيَنْتَفِضُ وَيَتَوَضَّأُ، وَلاَ يُصَلِّي حَتَّى يُصَلِّيَ بِجَمْعٍ‏.‏