(136) باب السُّرْعَةِ فِي السَّيْرِ
Narrated Aslam:
While I was in the company of `Abdullah bin `Umar on the way to Mecca, he received the news of the severe illness of Safiya bint Abi Ubaid (i.e. his wife), so he proceeded at greater speed, and when the twilight disappeared, he dismounted and offered the Maghrib and `Isha 'prayers together and said, " I saw the Prophet (ﷺ) delaying the Maghrib prayer to offer it along with the `Isha' when he was in a hurry on a journey."
Reference: Sahih al-Bukhari 3000
In-book reference: Book 56, Hadith 209
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 52, Hadith 244