Whenever the Messenger of Allah ﷺ was pressed for time while travelling, he would combine the Maghrib and Isha prayers.
كان رسول الله ﷺ إذا عجل به السير يجمع بين المغرب والعشاء.
Malik narrated it in "Shortening the Prayer" (3), from Nafi, from Abdullah bin Umar, as mentioned. Muslim narrated it in "Shortening the Prayer for Travelers" (703) through the route of Malik, with the same wording.The two sheikhs, Bukhari in "Shortening the Prayer" (1106) and Muslim, both narrated it from the hadith of Sufyan, from Zuhri, from Salim, from his father (that is, Abdullah bin Umar), who said, "The Prophet ﷺ used to combine Maghrib and Isha when he was pressed for time while traveling."They also both have it, Bukhari (1091) and Muslim, through two other routes from Zuhri, from Salim bin Abdullah, that his father said, "I saw the Messenger of Allah ﷺ, when travel pressed him, delay the Maghrib prayer until he combined it with the Isha prayer."In a version recorded by Muslim from the hadith of Ubaydullah, from Nafi, Ibn Umar, when travel pressed him, would combine Maghrib and Isha after the twilight had disappeared, and he would say, "The Messenger of Allah ﷺ, when travel pressed him, used to combine Maghrib and Isha."In the Musnad (5120), Ibn Umar was urgently summoned regarding Safiya while he was in Makkah. He traveled on until the sun set and the stars appeared, then he said, "The Prophet ﷺ, when a matter pressed him during a journey, would combine these two prayers." He kept traveling until the twilight disappeared, then he stopped and combined the two prayers.In Bukhari, as a suspended report (1092), it states that Ibn Umar delayed the Maghrib prayer, having been urgently summoned regarding his wife Safiya bint Abu Ubayd. I said to him (the speaker being Salim), "The prayer." He said, "Keep going." I said, "The prayer." He said, "Keep going," until he had traveled two or three miles. Then he stopped and prayed, and said, "This is how I saw the Prophet ﷺ pray when travel pressed him."He also narrated it with a connected chain in the Book of Jihad (3000), from Zayd bin Aslam, from his father, who said, "I was with Abdullah bin Umar on the road to Makkah, when news reached him that Safiya bint Abu Ubayd was gravely ill, so he hastened his travel. When it was after the twilight had disappeared, he stopped and prayed Maghrib and Isha together, combining them, and said, 'I saw the Prophet ﷺ, when travel pressed him, delay Maghrib and combine the two.'"Ibn Hajar said, "This narration establishes the specific journey mentioned, the time at which the travel ended, and explicitly states the combining of the two prayers." (Fath al-Bari, 2/573)Istasrakha (with a damma) means to call for help with a raised voice, which is sarakh (with the letter kha).Safiya is the daughter of Abu Ubayd, the wife of Abdullah bin Umar. She bore him Waqid, Abu Bakr, Abu Ubayda, Ubaydullah, Umar, Hafsa, and Sawda. She lived a long life and grew old, so that she used to go around on her mount.